def digest_chunk(chunk, branch=None):
    lines = chunk[0]
    key = 'Working file:'
    keylen = len(key)
    for line in lines:
        if line[:keylen] == key:
            working_file = line[keylen:].strip()
            break
    else:
        working_file = None
    if branch is None:
        pass
    elif branch == "HEAD":
        branch = re.compile(r"^\d+\.\d+$")
    else:
        revisions = {}
        key = 'symbolic names:\n'
        found = 0
        for line in lines:
            if line == key:
                found = 1
            elif found:
                if line[0] in '\t ':
                    tag, rev = line.split()
                    if tag[-1] == ':':
                        tag = tag[:-1]
                    revisions[tag] = rev
                else:
                    found = 0
        rev = revisions.get(branch)
        branch = re.compile(r"^<>$") # <> to force a mismatch by default
        if rev:
            if rev.find('.0.') >= 0:
                rev = rev.replace('.0.', '.')
                branch = re.compile(r"^" + re.escape(rev) + r"\.\d+$")
    records = []
    for lines in chunk[1:]:
        revline = lines[0]
        dateline = lines[1]
        text = lines[2:]
        words = dateline.split()
        author = None
        if len(words) >= 3 and words[0] == 'date:':
            dateword = words[1]
            timeword = words[2]
            if timeword[-1:] == ';':
                timeword = timeword[:-1]
            date = dateword + ' ' + timeword
            if len(words) >= 5 and words[3] == 'author:':
                author = words[4]
                if author[-1:] == ';':
                    author = author[:-1]
        else:
            date = None
            text.insert(0, revline)
        words = revline.split()
        if len(words) >= 2 and words[0] == 'revision':
            rev = words[1]
        else:
            # No 'revision' line -- weird...
            rev = None
            text.insert(0, revline)
        if branch:
            if rev is None or not branch.match(rev):
                continue
        records.append((date, working_file, rev, author, text))
    return records
Digest a chunk -- extract working file name and revisions
dataset/ETHPy150Open Southpaw-TACTIC/TACTIC/src/context/client/tactic-api-python-4.0.api04/Tools/Scripts/logmerge.py/digest_chunk