human
Here's a good function header given the following:
I wrote the below code

    def decode_line(line):
        if isinstance(line, bytes):
            try:
                line.decode('ascii')
            except UnicodeDecodeError:
                raise NetworkXError('input    is    not    ASCII-encoded')
        if (not isinstance(line, str)):
            line = str(line)
        return line
    def filter_lines(lines):
        if isinstance(lines, (str, unicode)):
            lines = decode_line(lines)
            lines = lines.splitlines()
            for line in lines:
                (yield line)
        else:
            for line in lines:
                line = decode_line(line)
                if (line and (line[(-1)] == '\n')):
                    line = line[:(-1)]
                if (line.find('\n') != (-1)):
                    raise NetworkXError('input    line    contains    newline')
                (yield line)
    G = parse_gml_lines(filter_lines(lines), label, destringizer)
    return G

What's a good function header?
assistant
#Here's a good function header.

def parse_gml(lines, label='label', destringizer=None):