def _extract_possible_header_from_line(line):
    """Given a `line` extract possible header.

    Args:
        line (str): Line containing header and message body.

    Returns:
        str: Possible header.

    """
    line_split = line.split(': ')
    if len(line_split) >= 2:
        header = line_split[0]
        if not header.isprintable():
            header = header.replace('\u200e', '').replace('\u202e', '')
        return header
    return None
