Give type of input line, as defined in LINE_TYPES

    >>> line_type('IN\\ta\\tb')
    'IN'
    >>> line_type('')
    'EMPTY'

def line_type(line:str) -> str:
    """Give type of input line, as defined in LINE_TYPES

    >>> line_type('IN\\ta\\tb')
    'IN'
    >>> line_type('')
    'EMPTY'

    """
    for regex, ltype in LINE_TYPES.items():
        if re.fullmatch(regex, line):
            return ltype
    raise ValueError("Input line \"{}\" is not bubble formatted".format(line))