import difflib


def quick_string_dist(a,b):
    """
    Computes a quick string distance between two given
    strings (a and b) using Python's difflib.
    """

    t=0
    for i in difflib.SequenceMatcher(None, a, b).get_opcodes():
        if i[0]=='equal': continue
        t=t+max(i[4]-i[3],i[2]-i[1])
    return t