def func():
    return 'hi'

func()

'hi'

def greet(who):
    return 'Hello, {}'.format(who)

greet('Alice')

'Hello, Alice'

def fibbonaci(n):
    """Compute Fibbonaci numbers"""
    if n <= 1:
        return 1
    else:
        return fibbonaci(n-1) + fibbonaci(n-2)

fibbonaci(7)

21

import math
def log(n, base=math.e):
    return math.log(n) / math.log(base)

log(8, 2)

3.0

log(8)

2.0794415416798357

math.log(8)

2.0794415416798357