Document the 'h' variable in our raw_feeder

def from_raw_reader(in_file, filter=lambda buf: buf):

    def feeder(out_file):

        max_lines = Config().max_diff_input_lines

        line_count = 0

        end_nl = False

        line_count = 0

        # If we have a maximum size, hash the content as we go along so we can

        # display a nicer message.

        h = None

        if max_lines < float('inf'):

            h = hashlib.sha1()

        for buf in in_file:

            line_count += 1

            out = filter(buf)

            if h:

            if h is not None:

                h.update(out)

            if line_count < max_lines:

                out_file.write(out)

            end_nl = buf[-1] == '\n'

        if h and line_count >= max_lines:

        if h is not None and line_count >= max_lines:

            out_file.write("[ Too much input for diff (SHA1: {}) ]\n".format(

                h.hexdigest(),

            ).encode('utf-8'))

            end_nl = True

        return end_nl

    return feeder