def string_dist(str1, str2):
    if str1 is None and str2 is None:
        return 0.0
    if str1 is None or str2 is None:
        return 1.0

    str1 = str1.lower()
    str2 = str2.lower()

    # Don't penalize strings that move certain words to the end. For
    # example, "the something" should be considered equal to
    # "something, the".
    for word in SD_END_WORDS:
        if str1.endswith(', %s' % word):
            str1 = '%s %s' % (word, str1[:-len(word) - 2])
        if str2.endswith(', %s' % word):
            str2 = '%s %s' % (word, str2[:-len(word) - 2])

    # Perform a couple of basic normalizing substitutions.
    for pat, repl in SD_REPLACE:
        str1 = re.sub(pat, repl, str1)
        str2 = re.sub(pat, repl, str2)

    # Change the weight for certain string portions matched by a set
    # of regular expressions. We gradually change the strings and build
    # up penalties associated with parts of the string that were
    # deleted.
    base_dist = _string_dist_basic(str1, str2)
    penalty = 0.0
    for pat, weight in SD_PATTERNS:
        # Get strings that drop the pattern.
        case_str1 = re.sub(pat, '', str1)
        case_str2 = re.sub(pat, '', str2)

        if case_str1 != str1 or case_str2 != str2:
            # If the pattern was present (i.e., it is deleted in the
            # the current case), recalculate the distances for the
            # modified strings.
            case_dist = _string_dist_basic(case_str1, case_str2)
            case_delta = max(0.0, base_dist - case_dist)
            if case_delta == 0.0:
                continue

            # Shift our baseline strings down (to avoid rematching the
            # same part of the string) and add a scaled distance
            # amount to the penalties.
            str1 = case_str1
            str2 = case_str2
            base_dist = case_dist
            penalty += weight * case_delta

    return base_dist + penalty
Given an original document and a set of exact duplicates, copies
dataset/ETHPy150Open beetbox/beets/beets/autotag/hooks.py/string_dist--crossover with--dataset/ETHPy150Open quip/quip-api/python/quip.py/QuipClient.merge_comments