Parse the negation modifier in an operation.

def parse_negation_operation(operation: str) -> Tuple[bool, str]:
    """Parse the negation modifier in an operation."""
    _operation = operation.strip()
    if not _operation:
        raise QueryParserException('Operation is not valid: {}'.format(operation))
    negation = False
    if _operation[0] == '~':
        negation = True
        _operation = _operation[1:]

    return negation, _operation.strip()