Python 3

# Variables are dynamically typed
age = 25              # int
price = 19.99         # float
name = "Alice"        # str
is_active = True      # bool

# f-Strings for formatting
greeting = f"Hello {name}, you are {age} years old."

# List: Ordered, Mutable
fruits = ["apple", "banana", "cherry"]
fruits.append("orange")

# Tuple: Ordered, Immutable
coordinates = (10.0, 20.0)

# Set: Unordered, Unique elements
ids = {1, 2, 3, 3, 4} # {1, 2, 3, 4}

# Dictionary: Key-Value pairs
user = {
    "name": "Bob",
    "age": 30
}
print(user["name"]) # Bob

# Conditionals
if age >= 18:
    print("Adult")
elif age >= 13:
    print("Teen")
else:
    print("Child")

# For Loop (Iterating over a list)
for fruit in fruits:
    print(fruit)

# For Loop (Range)
for i in range(5): # 0, 1, 2, 3, 4
    print(i)

# While Loop
while count > 0:
    print(count)
    count -= 1

def greet(name, msg="Hello"):
    """Docstring: Greets a person."""
    return f"{msg}, {name}!"

print(greet("Alice"))           # Hello, Alice!
print(greet("Bob", "Welcome"))  # Welcome, Bob!

# *args for variable positional arguments
def sum_all(*args):
    return sum(args)

# List Comprehension
squares = [x**2 for x in range(10)]
# [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

# With Condition
even_squares = [x**2 for x in range(10) if x % 2 == 0]

# Dictionary Comprehension
sq_dict = {x: x**2 for x in range(5)}
# {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

class Dog:
    # Class attribute
    species = "Canis familiaris"

    # Constructor
    def __init__(self, name, age):
        self.name = name
        self.age = age

    # Instance method
    def bark(self):
        return f"{self.name} says woof!"

# Instantiation
my_dog = Dog("Rex", 5)
print(my_dog.bark())