Scope of Variables

Scope refers to the region of a program where a variable is accessible. Python has two main scopes:

Scope	Where defined	Where accessible	Keyword to modify
Local Variable	Inside a function	Only within that function; not accessible outside	—
Global Variable	Outside all functions	Anywhere in the program (file)	global

x = 10              # Global variable

def show():

    y = 20          # Local variable

    print('x =', x) # Can access global x

    print('y =', y)

show()              # Output: x = 10  y = 20

# print(y)          # Error: y is not defined outside the function

# Modifying a global variable inside a function by using global keyword

count = 0

def increment():

    global count    # Declare we are using the global count

    count += 1

increment()

increment()

print(count)        # Output: 2

The return Statement

The return statement exits a function and optionally sends a value back to the caller.

Scenario	Behaviour	Example
return value	Exits function and returns the specified value to caller	return s
return (no value)	Exits function; caller receives None	return
No return at all	Function runs to end; caller receives None	(no return statement)
Multiple values	Returns a tuple; can be unpacked by caller	return x, y, z

# Return a single value

def square(n):

    return n * n

print(square(5))           # Output: 25

# Return multiple values

def min_max(lst):

    return min(lst), max(lst)

lo, hi = min_max([3, 1, 9, 5])

print('Min:', lo, 'Max:', hi)  # Output: Min: 1 Max: 9

# No return (returns None implicitly)

def say_hi():

    print('Hi!')

result = say_hi()          # Output: Hi!

print(result)              # Output: None