:param sequence: The input sequence.
    :type sequence: Seq
    :rtype: bool

def checkseq(sequence: str=None,  code="ATGC") -> bool:
    """
    :param sequence: The input sequence.
    :type sequence: Seq
    :rtype: bool
    """
    for base in sequence:
        if base not in code:
            return False
    return True