hamming_distance.py

# string1 and string2 should be the same length.
def hamming_distance(string1, string2): 
    # Start with a distance of zero, and count up
    distance = 0
    # Loop over the indices of the string
    L = len(string1)
    for i in range(L):
        # Add 1 to the distance if these two characters are not equal
        if string1[i] != string2[i]:
            distance += 1
    # Return the final count of differences
    return distance