Long code for hamming number

def hamming(s1,s2):
    """ returns the hamming number (char differences) between two strings """
    # initialize hamming distance to 0 and find min/max lengths
    hamming_number = 0
    minlength = min(len(s1),len(s2))
    maxlength = max(len(s1),len(s2))

    # iterate through strings up to minlength and compare by each char
    for i in range(minlength):
        if (s1[i] != s2[i]):
            hamming_number += 1

    # add remaining extra characters
    hamming_number += maxlength - minlength

    # return result
    return hamming_number