def greet(name):
    return f"Hello, {name}!"

if __name__ == "__main__":
    message = greet("world")
    print(message)

$ python hello.py

str_single = "Hello"
str_multiline = """Multiline
string"""
print(str_multiline.upper())

name = "John Doe"
print(name.lower())  # john doe
print(name.split())  # ['John', 'Doe']

integer = 42
floating_point = 3.14
complex_number = 2 + 3j

# Converting between types
float_to_int = int(3.7)  # 3

import numpy as np
array = np.array([1, 2, 3])
print(array.mean())  # 2.0

day = "sunday"

if day in ["sunday", "saturday"]:
    print("Rest!")
elif day == "monday" and is_tired():
    print("Groan!")
else:
    print("Work!")

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Cleanup complete.")

for i in range(5):
    print(f"Iteration {i}")

count = 0
while count < 5:
    print(f"Count is {count}")
    count += 1