def add(self, other):
        """Return the QuantumChannel self + other.

        Args:
            other (QuantumChannel): a quantum channel.

        Returns:
            SuperOp: the linear addition self + other as a SuperOp object.

        Raises:
            QiskitError: if other cannot be converted to a channel or
            has incompatible dimensions.
        """
        # Convert other to SuperOp
        if not isinstance(other, SuperOp):
            other = SuperOp(other)
        if self.dim != other.dim:
            raise QiskitError("other QuantumChannel dimensions are not equal")
        return SuperOp(self._data + other.data, self.input_dims(),
                       self.output_dims())
Return the QuantumChannel self + other.

        Args:
            other (QuantumChannel): a quantum channel.

        Returns:
            SuperOp: the linear addition self + other as a SuperOp object.

        Raises:
            QiskitError: if other cannot be converted to a channel or
            has incompatible dimensions.