2.4. Return Statement

All functions inherently return a value. If a return statement is absent in a function, the None data type is automatically returned by default.

def f(x):
    x = x * 2

res = f(3)
res

print(res)
id(res)

None

9678144

def f(x):
    x = x * 2
    return None

print(f(3))

None