diff --git a/Python/Standard Library/collections.md b/Python/Standard Library/collections.md
index 9c36a2e..1494033 100644
--- a/Python/Standard Library/collections.md	
+++ b/Python/Standard Library/collections.md	
@@ -1,78 +1,78 @@
-
-# Collections Module
-
-```py
-# COUNTER()
-# sottoclasse dizionario per contare oggetti hash-abili
-from collections import Counter
-Counter(sequenza)  # -> oggetto Counter
-# {item: num comprese in sequenza, ...}
-
-var = Counter(sequenza)
-var.most_common(n)  # produce lista degli elementi più comuni (n più comuni)
-sum(var.values())  # totale di tutti i conteggi
-var.clear()  #reset tutti i conteggi
-list(var)  # elenca elementi unici
-set(var)  # converte in un set
-dict(var)   # converte in un dizionario regolare
-var.items()  # converte in una lista di coppie (elemento, conteggio)
-Counter(dict(list_of_pairs))  # converte da una lista di coppie
-var.most_common[:-n-1:-1]  # n elementi meno comuni
-var += Counter()  # rimuove zero e conteggi negativi
-
-
-# DEFAULTDICT()
-# oggetto simil-dizionario che come primo argomento prende un tipo di default
-# defaultdict non solleverà mai un eccezione KeyError.
-# le chiavi non esistenti ritornano un valore di default (default_factory)
-from collections import defaultdict
-var = defaultdict(default_factory)
-var.popitem()  # rimuove e restituisce primo elemento
-var.popitem(last=True) # rimuove e restituisce ultimo elemento
-
-
-# OREDERDDICT()
-# sottoclasse dizionario che "ricorda" l'ordine in cui vengono inseriti i contenuti
-# dizionari normali hanno ordinamento casuale
-nome_dict = OrderedDict()
-# OrderedDict con stessi elementi ma ordine diverso sono considerati diversi
-
-
-# USERDICT()
-# implementazione pura in pythondi una mappa che funziona come un normale dizionario.
-# Designata per creare sottoclassi
-UserDict.data  # recipiente del contenuto di UserDict
-
-
-# NAMEDTUPLE()
-# ogni namedtuple è rappresentata dalla propria classe
-from collections import namedtuple
-NomeClasse = namedtuple(NomeClasse, parametri_separati_da_spazio)
-var = NomeClasse(parametri)
-var.attributo  # accesso agli attributi
-var[index]  # accesso agli attributi
-var._fields  # accesso ad elenco attributi
-var = classe._make(iterabile)  # trasformain namedtuple
-var._asdict()  # restituisce oggetto OrderedDict a partire dalla namedtuple
-
-
-# DEQUE()
-# double ended queue (pronunciato "deck")
-# lista modificabuile da entrambi i "lati"
-from collections import deque
-var = deque(iterabile, maxlen=num)  # -> oggetto deque
-var.append(item)  # aggiunge item al fondo
-var.appendleft(item)  # aggiunge item all'inizio
-var.clear()  # rimuove tutti gli elementi
-var.extend(iterabile)  # aggiunge iterabile al fondo
-var.extendleft(iterabile)  # aggiunge iterabile all'inizio'
-var.insert(index, item)  # inserisce  in posizione index
-var.index(item, start, stop)  # restituisce posizione di item
-var.count(item)
-var.pop()
-var.popleft()
-var.remove(valore)
-var.reverse()  # inverte ordine elementi
-var.rotate(n)  # sposta gli elementi di n step (dx se n > 0, sx se n < 0)
-var.sort()
-```
+
+# Collections Module
+
+``` py
+# COUNTER ()
+# subclass dictionary for counting hash-capable objects
+from collections import Counter
+Counter (sequence) # -> Counter object
+# {item: num included in sequence, ...}
+
+var = Counter (sequence)
+var.most_common (n) # produce list of most common elements (most common n)
+sum (var.values ​​()) # total of all counts
+var.clear () #reset all counts
+list (var) # list unique items
+set (var) # convert to a set
+dict (var) # convert to regular dictionary
+var.items () # convert to a list of pairs (element, count)
+Counter (dict (list_of_pairs)) # convert from a list of pairs
+var.most_common [: - n-1: -1] # n less common elements
+var + = Counter () # remove zero and negative counts
+
+
+# DEFAULTDICT ()
+# dictionary-like object that takes a default type as its first argument
+# defaultdict will never raise a KeyError exception.
+# non-existent keys return a default value (default_factory)
+from collections import defaultdict
+var = defaultdict (default_factory)
+var.popitem () # remove and return first element
+var.popitem (last = True) # remove and return last item
+
+
+# OREDERDDICT ()
+# subclass dictionary that "remembers" the order in which the contents are entered
+# Normal dictionaries have random order
+name_dict = OrderedDict ()
+# OrderedDict with same elements but different order are considered different
+
+
+# USERDICT ()
+# pure implementation in pythondi a map that works like a normal dictionary.
+# Designated to create subclasses
+UserDict.data # recipient of UserDict content
+
+
+# NAMEDTUPLE ()
+# each namedtuple is represented by its own class
+from collections import namedtuple
+NomeClasse = namedtuple (NomeClasse, parameters_separated_from_space)
+var = ClassName (parameters)
+var.attribute # access to attributes
+var [index] # access to attributes
+var._fields # access to attribute list
+var = class._make (iterable) # transformain namedtuple
+var._asdict () # Return OrderedDict object starting from namedtuple
+
+
+# DEQUE ()
+# double ended queue (pronounced "deck")
+# list editable on both "sides"
+from collections import deque
+var = deque (iterable, maxlen = num) # -> deque object
+var.append (item) # add item to the bottom
+var.appendleft (item) # add item to the beginning
+var.clear () # remove all elements
+var.extend (iterable) # add iterable to the bottom
+var.extendleft (iterable) # add iterable to the beginning '
+var.insert (index, item) # insert index position
+var.index (item, start, stop) # returns position of item
+var.count (item)
+var.pop ()
+var.popleft ()
+var.remove (value)
+var.reverse () # reverse element order
+var.rotate (n) # move the elements of n steps (dx if n> 0, sx if n <0)
+var.sort ()
+```
diff --git a/Python/Standard Library/csv.md b/Python/Standard Library/csv.md
index 6358141..fbdd2b4 100644
--- a/Python/Standard Library/csv.md	
+++ b/Python/Standard Library/csv.md	
@@ -1,82 +1,83 @@
-# CSV Module Cheat Sheet
-
-```python
-# itera linee di csvfile
-.reader(csvfile, dialect, **fmtparams) --> oggetto reader
-
-# METODI READER
-.__next__()  # restituisce prossima riga dell'oggetto iterabile come una lista o un dizionario
-
-# ATTRIBUTI READER
-dialect  # descrizione read-only del dialec usato
-line_num  # numero di linee dall'inizio dell'iteratore
-fieldnames
-
-# converte data in stringhe delimitate
-# csvfile deve supportare .write()
-#tipo None convertito a stringa vuota (semplifica dump di SQL NULL)
-.writer(csvfile, dialect, **fmtparams) --> oggetto writer
-
-# METODI WRITER
-# row deve essere iterabile di stringhe o numeri oppure dei dizionari
-.writerow(row)  # scrive row formattata secondo il dialect corrente
-.writerows(rows)  # scrive tutti gli elementi in rows formattati secondo il dialect corrente. rows è iterdabile di row
-
-# METODI CSV
-# associa dialect a name (name deve essere stringa)
-.register_dialect(name, dialect, **fmtparams)
-
-# elimina il dialect associato a name
-.unregister_dialect()
-
-# restituisce il dialetto associato a name
-.get_dialect(name)
-
-# elenco dialetti associati a name
-.list_dialect(name)
-
-# restituisce (se vuoto) o setta il limite del campo del csv
-.field_size_limit(new_limit)
-
-'''
-csvfile    --oggetto iterabile restituente una string ad ogni chiamata di __next__()
-          se csv è un file deve essere aperto con newline='' (newline universale)
-dialect    --specifica il dialetto del csv (Excel, ...) (OPZIONALE)
-
-fmtparams    --override parametri di formattazione (OPZIONALE)   https://docs.python.org/3/library/csv.html#csv-fmt-params
-'''
-
-# oggetto operante come reader ma mappa le info in ogni riga in un OrderedDict le cui chiavi sono opzionali e passate tramite fieldnames
-class csv.Dictreader(f, fieldnames=None, restket=none, restval=None, dialect, *args, **kwargs)
-'''
-f    --file da leggere
-fieldnames    --sequenza, definisce i nomi dei campi del csv. se omesso usa la prima linea di f
-restval, restkey    --se len(row) > fieldnames dati in eccesso memorizzati in restval e restkey
-
-parametri aggiuntivi passati a istanza reader sottostante
-'''
-
-class csv.DictWriter(f, fieldnames, restval='', extrasaction, dialect, *args, **kwargs)
-'''
-f    --file da leggere
-fieldnames    --sequenza, definisce i nomi dei campi del csv. (NECESSARIO)
-restval    --se len(row) > fieldnames dati in eccesso memorizzati in restval e restkey
-extrasaction    --se il dizionario passato a writerow() contiene key non presente in fieldnames extrasaction decide azione da intraprendere (raise causa valueError, ignore ignora le key aggiuntive)
-
-parametri aggiuntivi passati a istanza writer sottostante
-'''
-
-# METODI DICTREADER
-.writeheader()  # scrive una riga di intestazione di campi come specificato da fieldnames
-
-# classe usata per dedurre il formato del CSV
-class csv.Sniffer
-.sniff(campione, delimiters=None)  #analizza il campione e restituisce una classe Dialect. delimiter è sequenza di possibili delimitatori di caselle
-.has_header(campione) --> bool  # True se prima riga è una serie di intestazioni di colonna
-
-#COSTANTI
-csv.QUOTE_ALL  # indica a writer di citare (" ") tutti i campi
-csv.QUOTE_MINIMAL  # indica a write di citare solo i campi contenenti caratteri speciali come delimiter, quote char ...
-csv.QUOTE_NONNUMERIC  # indica al writer di citare tutti i campi non numerici
-csv.QUOTE_NONE  # indica a write di non citare mai i campi
-```
+
+# CSV Module Cheat Sheet
+
+``` python
+# iterate lines of csvfile
+.reader (csvfile, dialect, ** fmtparams) -> reader object
+
+# READER METHODS
+.__ next __ () # returns next iterable object line as a list or dictionary
+
+# READER ATTRIBUTES
+dialect # read-only description of the dialec used
+line_num # number of lines from the beginning of the iterator
+fieldnames
+
+# convert data to delimited strings
+# csvfile must support .write ()
+#type None converted to empty string (simplify SQL NULL dump)
+.writer (csvfile, dialect, ** fmtparams) -> writer object
+
+# WRITER METHODS
+# row must be iterable of strings or numbers or of dictionaries
+.writerow (row) # write row formatted according to the current dialect
+.writerows (rows) # write all elements in rows formatted according to the current dialect. rows is iterable of row
+
+# CSV METHODS
+# associate dialect to name (name must be string)
+.register_dialect (name, dialect, ** fmtparams)
+
+# delete the dialect associated with name
+.unregister_dialect ()
+
+# returns the dialect associated with name
+.get_dialect (name)
+
+# list of dialects associated with name
+.list_dialect (name)
+
+# returns (if empty) or sets the limit of the csv field
+.field_size_limit (new_limit)
+
+'''
+csvfile - iterable object returning a string on each __next __ () call
+          if csv is a file it must be opened with newline = '' (universal newline)
+dialect - specify the dialect of csv (Excel, ...) (OPTIONAL)
+
+fmtparams --override formatting parameters (OPTIONAL) https://docs.python.org/3/library/csv.html#csv-fmt-params
+'''
+
+# object operating as a reader but maps the info in each row into an OrderedDict whose keys are optional and passed through fieldnames
+class csv.Dictreader (f, fieldnames = None, restket = none, restval = None, dialect, * args, ** kwargs)
+'''
+f - files to read
+fieldnames --sequence, defines the names of the csv fields. if omitted use the first line of f
+restval, restkey --se len (row)> fieldnames excess data stored in restval and restkey
+
+additional parameters passed to the underlying reader instance
+'''
+
+class csv.DictWriter (f, fieldnames, restval = '', extrasaction, dialect, * args, ** kwargs)
+'''
+f - files to read
+fieldnames --sequence, defines the names of the csv fields. (NECESSARY)
+restval --se len (row)> fieldnames excess data stored in restval and restkey
+extrasaction - if the dictionary passed to writerow () contains key not present in fieldnames extrasaction decides action to be taken (raise cause valueError, ignore ignores additional keys)
+
+additional parameters passed to the underlying writer instance
+'''
+
+# DICTREADER METHODS
+.writeheader () # write a header line of fields as specified by fieldnames
+
+# class used to infer the format of the CSV
+class csv.Sniffer
+.sniff (sample, delimiters = None) #parse the sample and return a Dialect class. delimiter is a sequence of possible box delimiters
+.has_header (sample) -> bool # True if first row is a series of column headings
+
+#CONSTANTS
+csv.QUOTE_ALL # instructs writer to quote ("") all fields
+csv.QUOTE_MINIMAL # instructs write to quote only fields containing special characters such as delimiter, quote char ...
+csv.QUOTE_NONNUMERIC # instructs the writer to quote all non-numeric fields
+csv.QUOTE_NONE # instructs write to never quote fields
+```
diff --git a/Python/Standard Library/itertools.md b/Python/Standard Library/itertools.md
index 09ea333..a9e108a 100644
--- a/Python/Standard Library/itertools.md	
+++ b/Python/Standard Library/itertools.md	
@@ -1,72 +1,72 @@
-# Itertools Module
-
-```py
-# accumulate([1,2,3,4,5]) -> 1, 3(1+2), 6(1+2+3), 10(1+2+3+6), 15(1+2+3+4+5)
-# accumulate(iter, func( , )) -> iter[0], func(iter[0] + iter[1]) + func(prev + iter[2]), ...
-accumulate(iterable, func(_, _))
-
-# iteratore restituisce elementi dal primo iterable,
-# poi procede al successivo fino alla fine degli iterabili
-# non funziona se l'iterable è uno solo
-chain(*iterabili)
-
-# concatena elementi del singolo iterable anche se contiene sequenze
-chain.from_iterable(iterable)
-
-# restituisce sequenze di lunghezza r a partire dall'iterable
-# elementi trattati come unici in base al loro valore
-combinations(iterable, r)
-
-# # restituisce sequenze di lunghezza r a partire dall'iterable permettendo la ripetizione degli elementi
-combinations_with_replacement(iterable, r)
-
-# iteratore filtra elementi di data restituendo solo quelli che hanno
-#  un corrispondente elemento in selectors che ha valore vero
-compress(data, selectors)
-
-count(start, step)
-
-# iteratore restituente valori in sequenza infinita
-cycle(iterable)
-
-# iteratore scarta elementi dell'iterable finché il predicato è vero
-dropwhile(predicato, iterable)
-
-# iteratore restituente valori se il predicato è falso
-filterfalse(predicato, iterable)
-
-# iteratore restituisce tuple (key, group)
-# key è il criterio di raggruppamento
-# group è un generatore restituente i membri del gruppo
-groupby(iterable, key=None)
-
-# iteratore restituisce slice dell'iterable
-isslice(iterable, stop)
-isslice(iterable, start, stop, step)
-
-# restituisce tutte le permutazioni di lunghezza r dell'iterable
-permutations(iterable, r=None)
-
-# prodotto cartesiano degli iterabili
-# cicla iterabili in ordine di input
-# [product('ABCD', 'xy') -> Ax Ay Bx By Cx Cy Dx Dy]
-# [product('ABCD', repeat=2) -> AA AB AC AD BA BB BC BD CA CB CC CD DA DB DC DD]
-product(*iterabili, ripetizioni=1)
-
-# restituisce un oggetto infinite volte se ripetizioni non viene specificato
-repeat(oggetto, ripetizioni)
-
-# iteratore computa func(iterable)
-# usato se iterable è sequenza pre-zipped (seq di tuple raggruppanti elementi)
-starmap(func, iterable)
-
-# iteratore restituente valori da iterable finché predicato è vero
-takewhile(predicato, iterable)
-
-# restituisce n iteratori indipendenti dal singolo iterable
-tee(iterable, n=2)
-
-# produce un iteratore che aggrega elementi da ogni iterable
-# se gli iterabili hanno lunghezze differenti i valori mancanti sono riempiti secondo fillervalue
-zip_longest(*iterable, fillvalue=None)
-```
+# Itertools Module
+
+``` py
+# accumulate ([1,2,3,4,5]) -> 1, 3 (1 + 2), 6 (1 + 2 + 3), 10 (1 + 2 + 3 + 6), 15 (1+ 2 + 3 + 4 + 5)
+# accumulate (iter, func (,)) -> iter [0], func (iter [0] + iter [1]) + func (prev + iter [2]), ...
+accumulate (iterable, func (_, _))
+
+# iterator returns elements from the first iterable,
+# then proceeds to the next until the end of the iterables
+# does not work if there is only one iterable
+chain (* iterable)
+
+# concatenates elements of the single iterable even if it contains sequences
+chain.from_iterable (iterable)
+
+# returns sequences of length r starting from the iterable
+# items treated as unique based on their value
+combinations (iterable, r)
+
+# # returns sequences of length r starting from the iterable allowing the repetition of the elements
+combinations_with_replacement (iterable, r)
+
+# iterator filters date elements returning only those that have
+# a corresponding element in selectors that is true
+compress (data, selectors)
+
+count (start, step)
+
+# iterator returning values ​​in infinite sequence
+cycle (iterable)
+
+# iterator discards elements of the iterable as long as the predicate is true
+dropwhile (predicate, iterable)
+
+# iterator returning values ​​if predicate is false
+filterfalse (predicate, iterable)
+
+# iterator returns tuple (key, group)
+# key is the grouping criterion
+# group is a generator returning group members
+groupby (iterable, key = None)
+
+# iterator returns slices of the iterable
+isslice (iterable, stop)
+isslice (iterable, start, stop, step)
+
+# returns all permutations of length r of the iterable
+permutations (iterable, r = None)
+
+# Cartesian product of iterables
+# loops iterables in order of input
+# [product ('ABCD', 'xy') -> Ax Ay Bx By Cx Cy Dx Dy]
+# [product ('ABCD', repeat = 2) -> AA AB AC AD BA BB BC BD CA CB CC CD DA DB DC DD]
+product (* iterable, repetitions = 1)
+
+# returns an object infinite times if repetition is not specified
+repeat (object, repetitions)
+
+# iterator compute func (iterable)
+# used if iterable is pre-zipped sequence (seq of tuples grouping elements)
+starmap (func, iterable)
+
+# iterator returning values ​​from iterable as long as predicate is true
+takewhile (predicate, iterable)
+
+# returns n independent iterators from the single iterable
+tee (iterable, n = 2)
+
+# produces an iterator that aggregates elements from each iterable
+# if the iterables have different lengths the missing values ​​are filled according to fillervalue
+zip_longest (* iterable, fillvalue = None)
+```
diff --git a/Python/Standard Library/operator.md b/Python/Standard Library/operator.md
deleted file mode 100644
index 8d40f91..0000000
--- a/Python/Standard Library/operator.md	
+++ /dev/null
@@ -1,44 +0,0 @@
-# Operator Module Cheat Sheet
-
-```py
-# OPERATORI CONFRONTO
-__lt__(a, b), lt(a, b)  # a < b
-__le__(a, b), le(a, b)  # a <= b
-__eq__(a, b), eq(a, b)  # a == b
-__ne__(a, b), ne(a, b)  # a != b
-__ge__(a, b), ge(a, b)  # a >= b
-__gt__(a, b), gt(a, b)  # a > b
-
-
-not_(obj)
-truth(obj)
-is_(a, b)
-is_not(a, b)
-
-
-__abs__(a, b), abs(obj)
-__add__(a, b), add(a, b)  # a + b
-__sub__(a, b), sub(a, b)  # a - b
-__mul__(a,b), mul(a,b)  # a * b
-__mul__(a, b), pow(a,b)  # a ** b
-__truediv__(a, b), truediv(a, b)  # a / b
-__floordiv__(a, b), floordiv(a, b)  # return a // b
-__mod__(a, b), mod(a, b)  # a % b
-__neg__(obj), neg(obj)  # -obj
-__index__(a), index(a)
-
-__and__(a, b), and_(a, b)  # a & b
-__or__(a, b), or_(a, b)  # a | b
-__xor__(a, b), xor(a, b)  # a ^ b
-
-__inv__(obj), inv(obj), __inverse__(obj), inverse(obj)  # ~obj
-__lshift__(obj), lshift(a, b)
-
-__concat__(a, b), concat(a, b) 
-__contains__(a, b), contains(a, b)
-countOf(a, b)
-indexOf(a, b)
-
-__delitem__(a, b), delitem(a, b)
-__getitem__(a, b), getitem(a, b)
-__setitem__(a, b), setitem(a, b)
diff --git a/Python/Standard Library/time_datetime.md b/Python/Standard Library/time_datetime.md
index 7d0f302..762d0cf 100644
--- a/Python/Standard Library/time_datetime.md	
+++ b/Python/Standard Library/time_datetime.md	
@@ -1,64 +1,64 @@
-# Time & Datetime
-
-## Time
-
-```py
-# epoch: tempo in secondi trascorso (in UNIX parte da 01-010-1970)
-import time  # UNIX time
-variabile = time.time()  # restituisce il tempo (In secondi) trascorso da 01-01-1970
-variabile = time.ctime(epochseconds)  # trasforma l'epoca in data
-
-var = time.perf_counter()  # ritorna il tempo di esecuzione attuale
-# tempo di esecuzione = tempo inizio - tempo fine
-```
-
-### time.srtfrime() format
-
-| Format | Data                                                                                                       |
-|--------|------------------------------------------------------------------------------------------------------------|
-| `%a`   | Locale's abbreviated weekday name.                                                                         |
-| `%A`   | Locale's full weekday name.                                                                                |
-| `%b`   | Locale's abbreviated month name.                                                                           |
-| `%B`   | Locale's full month name.                                                                                  |
-| `%c`   | Locale's appropriate date and time representation.                                                         |
-| `%d`   | Day of the month as a decimal number `[01,31]`.                                                            |
-| `%H`   | Hour (24-hour clock) as a decimal number `[00,23]`.                                                        |
-| `%I`   | Hour (12-hour clock) as a decimal number `[01,12]`.                                                        |
-| `%j`   | Day of the year as a decimal number `[001,366]`.                                                           |
-| `%m`   | Month as a decimal number `[01,12]`.                                                                       |
-| `%M`   | Minute as a decimal number `[00,59]`.                                                                      |
-| `%p`   | Locale's equivalent of either AM or PM.                                                                    |
-| `%S`   | Second as a decimal number `[00,61]`.                                                                      |
-| `%U`   | Week number of the year (Sunday as the first day of the week) as a decimal number `[00,53]`.               |
-| `%w`   | Weekday as a decimal number `[0(Sunday),6]`.                                                               |
-| `%W`   | Week number of the year (Monday as the first day of the week) as a decimal number `[00,53]`.               |
-| `%x`   | Locale's appropriate date representation.                                                                  |
-| `%X`   | Locale's appropriate time representation.                                                                  |
-| `%y`   | Year without century as a decimal number `[00,99]`.                                                        |
-| `%Y`   | Year with century as a decimal number.                                                                     |
-| `%z`   | Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM |
-| `%Z`   | Time zone name (no characters if no time zone exists).                                                     |
-| `%%`   | A literal `%` character.                                                                                   |
-
-## Datetime
-
-```py
-import datetime
-today = datetime.date.today()   # restituisce data corrente
-today = datetime.datetime.today()  # restituisce la data e l'ora corrente
-
-# esempio di formattazione
-print('Current Date: {}-{}-{}' .format(today.day, today.month, today.year))
-print('Current Time: {}:{}.{}' .format(today.hour, today.minute, today.second))
-
-var_1 = datetime.date(anno, mese, giorno)  # crea oggetto data
-var_2 = datetime.time(ora, minuti, secondi, micro-secondi)  # crea oggetto tempo
-dt = datetime.combine(var_1, var_2)  # combina gli oggetti data e tempo in un unico oggetto
-
-date_1 = datetime.date('year', 'month', 'day')
-date_2 = date_1.replace(year = 'new_year')
-
-#DATETIME ARITHMETIC
-date_1 - date_2  # -> datetime.timedelta(num_of_days)
-datetime.timedelta  # durata esprimente differenza tra due oggetti date, time o datetime
-```
+# Time & Datetime
+
+## Time
+
+```py
+# epoch: elapsed time in seconds (in UNIX starts from 01-010-1970)
+import time # UNIX time
+variable = time.time () # returns the time (in seconds) elapsed since 01-01-1970
+variable = time.ctime (epochseconds) # transform epoch into date
+
+var = time.perf_counter () # returns the current running time
+# execution time = start time - end time
+```
+
+### time.srtfrime() format
+
+| Format | Data                                                                                                       |
+|--------|------------------------------------------------------------------------------------------------------------|
+| `%a`   | Locale's abbreviated weekday name.                                                                         |
+| `%A`   | Locale's full weekday name.                                                                                |
+| `%b`   | Locale's abbreviated month name.                                                                           |
+| `%B`   | Locale's full month name.                                                                                  |
+| `%c`   | Locale's appropriate date and time representation.                                                         |
+| `%d`   | Day of the month as a decimal number `[01,31]`.                                                            |
+| `%H`   | Hour (24-hour clock) as a decimal number `[00,23]`.                                                        |
+| `%I`   | Hour (12-hour clock) as a decimal number `[01,12]`.                                                        |
+| `%j`   | Day of the year as a decimal number `[001,366]`.                                                           |
+| `%m`   | Month as a decimal number `[01,12]`.                                                                       |
+| `%M`   | Minute as a decimal number `[00,59]`.                                                                      |
+| `%p`   | Locale's equivalent of either AM or PM.                                                                    |
+| `%S`   | Second as a decimal number `[00,61]`.                                                                      |
+| `%U`   | Week number of the year (Sunday as the first day of the week) as a decimal number `[00,53]`.               |
+| `%w`   | Weekday as a decimal number `[0(Sunday),6]`.                                                               |
+| `%W`   | Week number of the year (Monday as the first day of the week) as a decimal number `[00,53]`.               |
+| `%x`   | Locale's appropriate date representation.                                                                  |
+| `%X`   | Locale's appropriate time representation.                                                                  |
+| `%y`   | Year without century as a decimal number `[00,99]`.                                                        |
+| `%Y`   | Year with century as a decimal number.                                                                     |
+| `%z`   | Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM |
+| `%Z`   | Time zone name (no characters if no time zone exists).                                                     |
+| `%%`   | A literal `%` character.                                                                                   |
+
+## Datetime
+
+```py
+import datetime
+today = datetime.date.today () # returns current date
+today = datetime.datetime.today () # returns the current date and time
+
+# formatting example
+print ('Current Date: {} - {} - {}' .format (today.day, today.month, today.year))
+print ('Current Time: {}: {}. {}' .format (today.hour, today.minute, today.second))
+
+var_1 = datetime.date (year, month, day) # create date object
+var_2 = datetime.time (hour, minute, second, micro-second) # create time object
+dt = datetime.combine (var_1, var_2) # combine date and time objects into one object
+
+date_1 = datetime.date ('year', 'month', 'day')
+date_2 = date_1.replace (year = 'new_year')
+
+#DATETIME ARITHMETIC
+date_1 - date_2 # -> datetime.timedelta (num_of_days)
+datetime.timedelta # duration expressing the difference between two date, time or datetime objects
+```