def pauli_wt(pauli):
    """
    Return weight of given Pauli operator(s).

    :param pauli: A single or list of Pauli operators.
    :type pauli: str or list of str
    :return: Weight
    :rtype: int
    """

    def _wt(p):
        return p.count('X') + p.count('Y') + p.count('Z')

    if isinstance(pauli, str):
        return _wt(pauli)
    else:
        return sum(_wt(p) for p in pauli)