import numpy as np

def levenshtein_distance(s, t):
    if s == "":
        return len(t)

    if t == "":
        return len(s)

    if s[-1] == t[-1]:
        cost = 0
    else:
        cost = 1

    res = min([levenshtein_distance(s[:-1], t)+1,
               levenshtein_distance(s, t[:-1])+1, 
               levenshtein_distance(s[:-1], t[:-1]) + cost])
    return res

levenshtein_distance("Python", "Pithon")

1

levenshtein_distance("Canada", "Kanata")

2

levenshtein_distance("Australia", "Boston")

7

levenshtein_distance("Peter", "Beat It")

5