>> 'hello ali'.split()
['hello', 'ali']

>> 'Hello ali'.replace('Hello', 'Bye')
'Bye ali'

>> '-'.join(['a', 'b', 'c'])
'a-b-c'

>> 'Hello'.upper()
'HELLO'

>> """This is 
a multi-line
text"""
'This is \na multi-line\ntext'

>> a = "Hello, World!"
>> a[0]
'H'
>> a[::-1]
'!dlroW ,olleH'

>> name = 'ali'
>> 'Hello' + ' ' + name
'Hello ali'

>> "Hello %s" % name
'Hello ali'

>> 'Hello {}'.format(name)
'Hello ali'

>> f'Hello {name}'
'Hello ali'

>> thislist = ['🍎', '🍓', '🍐', '🍎', '🍎', '🍓']

>> len(thislist)
6

>> thislist[0]
'🍎'

>> thislist[1:3]
['🍓', '🍐']

>> thislist[-1]
'🍓'

>> thislist.append('🍑')

>> thislist
['🍎', '🍓', '🍐', '🍎', '🍎', '🍓', '🍑']

>> precedence = ['🥚', '🐔']

>> precedence.sort()

>> precedence

['🐔', '🥚']

>> a, b, c = ['🍎', '🍓', '🍐']
>> a
'🍎'
>> b
'🍓'
>> c
'🍐'

>> a, *b, c = ['🍎', '🍑', '🍓', '🍐']
>> b
['🍑', '🍓']

>> a, b = ['🍐', '🍎']
>> a, b = b, a # swap variables
>> a
'🍎'
>> b
'🍐'

>> first_set = {'🍎', '🍓', '🍐', '🍎', '🍎', '🍓'}

>> first_set
{'🍎', '🍐', '🍓'}

>> second_set = set(['🍌', '🍆', '🍓'])

>> third_set = second_set | first_set  # union

>> third_set
{'🍆', '🍌', '🍎', '🍐', '🍓'}

>> second_set & first_set
{'🍓'}

>> second_set < third_set 
True

>> dict1 = {'🍎': 5, '🍓': 3, '🍐':0}

>> dict1['🍓']
3

>> dict1['🍓'] = dict1['🍓'] - 1

>> del dict1['🍓']

>> car = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964,
  "year": 2020
}
>> car
{'brand': 'Ford', 'model': 'Mustang', 'year': 2020}

>> tuple_a = (1, 2, 3)
>> hash(tuple_a)
2528502973977326415

>> tuple_b = (2, 3, 4)
>> hash(tuple_b)
3789705017596477050

>> tuple_c = (1, 2, 3)
>> hash(tuple_c)
2528502973977326415

>> id(a) == id(c)
False # different objects.

>> hash(tuple_a == hash(tuple_c)
True # same value.

>> dict_a = {}
>> dict_a[tuple_a] = 'hiahia'
>> dict_a[tuple_c]
'hiahia'

>> a = [1,2,3]

>> hash(a)

TypeError: unhashable type: 'list'
    
>> b = {'a':1, 'b': 10}

>> hash(b)

TypeError: unhashable type: 'dict'
    
    
>> c = 123

>> hash(c)
123

>> d = 3.14

>> hash(d)
322818021289917443

a = 200
b = 33
if b > a:
  print("b is greater than a")
elif a == b:
  print("a and b are equal")
else:
  print("a is greater than b")

print("Positive" if a > 0 else "Negative")

print("A" if a > b else "=" if a == b else "B")

i = 0
while True:
    i += 1
    if i == 3:
        continue
    
    if i == 6:
        break
    print(i)
    
    
# 1  
# 2
# 4
# 5

i = 0
while i < 5:
    print(i**2)
    i += 1
else:
    print('done')
    
    
    
# 0
# 1
# 4
# 9
# 16
# done

string = "Lorem ipsum dolor sit amet"
if (n := len(string)) > 10:
    print(f"List is too long ({n} elements, expected <= 10)")

while (x := input('Enter a number: ')) != '0':
    print('Blah Blah Blah')

fruits = ["apple", "banana", "cherry"]

for x in fruits:
  print(x)
  
for i in range(6):
  print(i)

y = [x**2 for x in range(10)]

z = [x for x in range(10) if x % 2 == 0]

z = [x if x % 5!= 0 else 'HOP' for x in range(1, 11)]

adj = ["red", "big", "tasty"]
fruits = ["apple", "banana", "cherry"]

for x in adj:
  for y in fruits:
    print(x, y)

z = [x**y for x in range(5) for y in range(2, 5)]

def f(x, y):
  return x**2 + y ** 0.5

print(f(1, 2))

print(f(x = 1, y = 2))

print(f(1, y = 2))

y = lambda x: x**2

def my_function(country = "Iran"):
  print("I am from " + country)

my_function("Norway")  # I am from Norway
my_function() # I am from Iran

def area(radius: float) -> float:
    return 3.14 * radius ** 2

def prod(*numbers):
    r = 1
    for number in numbers:
        r *= number
    return r
  
print(prod(1, 2, 3, 4)) # 24

def print_price(**computers):
    for key in computers:
        print('{:4s} - {:.2f}'.format(key, computers[key]))
        
print_price(dell = 1299.50, asus = 1870.00, hp = 1990.50)

def func(a, b, *, c=10, **kwargs):
    # do something
    return 

def pow(x, *, y):
    return x**y

pow(3, y=2)
pow(x=3, y=2)

def f(x):
  return x ** 2

x = [1,2,3,4]

map(f, x) # a generator

fx = list(map(f, x))  # [1, 4, 9, 16]

even_numbers = list(filter(lambda x: x % 2 == 0, x))   # [2, 4]

minimum = min(x) #  1

rev = list(reversed(x))  # [4, 3, 2, 1]

names = ['ali', 'hasan', 'reza']
ages = [25, 22, 30]

pair= list(zip(names,ages)) # [('ali',25),('hasan',22),('reza',30)]

pair_dict = dict(pair)    # {'ali': 25, 'hasan': 22, 'reza': 30}

def func1():
    try:
        return 1
    finally:
        return 2

def func2():
    try:
        return 1
    except:
        return 2
    finally:
        return 3

func1(),func2() # 2, 3

x = 0
try:
    y = x / 0
except NameError as ex:
    print('x is not defined. Error:', ex)
except ZeroDivisionError:
    print('division by zero!')
else:
    print('code ran successfully')
finally:
    print('will run everytime')
    
    
# division by zero is not allowed
# will run everytime

def fast_prime_check(n):
    raise NotImplementedError('This method has not been implemented, yet.')
    
    
def circle_area(radius):
    assert radius > 0, ValueError('Radius must be positive.')
    return 3.14 * radius ** 2

file = open("demofile.txt", mode = 'r')
data = file.read()
file.close() # NEVER FORGET THIS


# Automatically close the file:
with open("demofile.txt", mode = 'r') as file:
  data = file.read()
  

# Create new files
with open("demofile.txt", mode = 'w') as file:
  file.write("Hello, World!")
  
  
# Append text to existing files
with open("demofile.txt", mode = 'a') as file:
  file.write("New Line.")

mytuple = ("apple", "banana", "cherry")
myit = iter(mytuple)

print(next(myit))
print(next(myit))
print(next(myit))

for x in mytuple:
  print(x)

def infinite_sequence():
    x = 0
    while True:
        yield 2 * x + 1
        x += 1

for x in infinite_sequence():
    print(x)
    if x > 20:
        break

def hello_decorator(func):
    def inner1(*args, **kwargs):
        print("before Execution")                 
        returned_value = func(*args, **kwargs)
        print("after Execution")
        return returned_value
    return inner1
 
 
@hello_decorator
def sum_two_numbers(a, b):
    print("Inside the function")
    return a + b
 
a, b = 1, 2
 
print("Sum =", sum_two_numbers(a, b))

# before Execution
# Inside the function
# after Execution
# Sum = 3

class Animal:
    def _init_(self, name):
        self.name = name

    def make_sound(self):
        raise NotImplementedError

    def get_greet_message(self):
        return f'Hello {self.name}'
      
    def __del__(self):
        print(f'Bye {self.name}')



class Dog(Animal):
    def make_sound(self):
        print('woof, woof.')

        
class Cat(Animal):
    def make_sound(self):
        print('Meow, Meow.')

>>dog = Dog('Lucy')

>>dog.get_greet_message()
>>'Hello Lucy'

>>dog.make_sound()
woof, woof.

>>del dog
Bye Lucy

def http_status(status):
    match status:
        case 400:
            return "Bad request"
        case 401:
            return "Unauthorized"
        case 403:
            return "Forbidden"
        case 404:
            return "Not found"

import math
a = math.sin(math.pi)

from math import sin, pi
b = sin(pi)

from math import *
c = cos(2 * pi)

import math as m
c = m.cos(2 * m.pi)

import time
import random

print(time.time()) # unix time

random.seed(time.time())

print(random.random()) # random float between 0 and 1

>> import re

>> re.match('\w+@\w+\.\w{2,4}', 'alirezaafzalaghaei@gmail.com')
<re.Match object; span=(0, 28), match='alirezaafzalaghaei@gmail.com'>

import sqlite3

try:
    sqliteConnection = sqlite3.connect('database.db')
    cursor = sqliteConnection.cursor()

    query = "SELECT sqlite_version();"
    cursor.execute(sqlite_select_Query)    
    record = cursor.fetchall()
    
    cursor.close()

except sqlite3.Error as error:
    print("Error while connecting to sqlite", error)
    
finally:
    if sqliteConnection:
        sqliteConnection.close()        

from multiprocessing import Pool

def f(x):
    return x**2

with Pool(4) as pool:
    res = pool.map(f, range(10))

    print(res)

import zipfile

with zipfile.ZipFile("hello.zip") as archive:
     archive.printdir()

from functools import reduce
import operator

prod = lambda *x: reduce(operator.mul, x)

prod(1,2,3) # 6

import random
from collections import Counter

def random_DNA(length=int()):        
  letters="CGTA"
  return''.join(random.choices(letters, k=length))

dna = random_DNA(20)            # AGTTTCACTGGATCCAATTG
counts = Counter(dna)
print(counts)                   # Counter({'T': 7, 'A': 5, 'G': 4, 'C': 4})
print(counts.most_common(2))    # [('T', 7), ('A', 5)]

$ pip install package_name

# Terminal:
# $ pip install requests BeautifulSoup4
# $ python

import requests
from bs4 import BeautifulSoup


url = "https://varzesh3.com/"

response = requests.get(url).content.decode('utf8')

soup = BeautifulSoup(response)

next_games = soup.select("div.league.football div.fixture-result-match")

# Terminal:
# $ pip install Selenium
# $ python

from selenium import webdriver

chrome = webdriver.Chrome()
chrome.get("https://maktabkhooneh.org")

user = {'email': 'a@b.cc','password': 'BlahBlahBlah'}
email.send_keys(user['email'])
password.send_keys(user['password'])
submit.click()

# Terminal:
# $ pip install opencv-python
# $ python

import cv2

img = cv2.imread('dumb.jpg')

dst = cv2.resize(img, (224, 224))

cv2.imshow('img', dst)

# Terminal:
# $ pip install flask
# $ python

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello_world():
    return "<p>Hello, World!</p>"

# Terminal:
# $ pip install pyqt5
# $ python

from PyQt5.QtWidgets import QApplication, QMainWindow
import sys
 
class Window(QMainWindow):
   def __init__(self):
       super().__init__()
 
       self.setGeometry(300, 300, 600, 400)
       self.setWindowTitle("PyQt5 window")
       self.show()
 
app = QApplication(sys.argv)
window = Window()
sys.exit(app.exec_())

# Terminal:
# $ pip install networkx
# $ python

import networkx as nx


g = nx.Graph()
g.add_edge(131,673,weight=673)
g.add_edge(131,201,weight=201)
g.add_edge(673,96,weight=96)
g.add_edge(201,96,weight=96)

nx.shortest_path(g, source=131, target=96, weight='weight')

# Terminal:
# $ pip install numpy
# $ python

import numpy as np

A = np.random.random(size=(3, 4)) # random matrix of the shape 2x4
B = np.eye(4) # Identity Matrix

C = A @ B  # Matrix Multiplication

D = C.reshape(-1, 6)  # reshaped 6x6 matrix

# Terminal:
# $ pip install matplotlib
# $ python

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 2 * np.pi, 10)
y = np.sin(x)

plt.plot(x, y)