def parse_file(file):
    """
    Take an open file containing the IANA subtag registry, and yield a
    dictionary of information for each subtag it describes.
    """
    lines = []
    for line in file:
        line = line.rstrip('\n')
        if line == '%%':
            # This is a separator between items. Parse the data we've
            # collected and yield the result.
            yield from parse_item(lines)
            lines.clear()
        elif line.startswith('  '):
            # This is a continuation line. Concatenate it to the previous
            # line, including one of the spaces.
            lines[-1] += line[1:]
        else:
            lines.append(line)
    yield from parse_item(lines)
Take an open file containing the IANA subtag registry, and yield a
    dictionary of information for each subtag it describes.