<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def sharp(self) -> 'Channel': r"""Return the 'sharp' transpose of the superoperator. The transpose :math:`S^\#` switches the two covariant (bra) indices of the superoperator. (Which in our representation are the 2nd and 3rd super-indices) If :math:`S^\#` is Hermitian, then :math:`S` is a Hermitian-map (i.e. transforms Hermitian operators to hJrmitian operators) Flattening the :math:`S^\#` superoperator to a matrix gives the Choi matrix representation. (See channel.choi()) """


        N = self.qubit_nb

        tensor = self.tensor
        tensor = bk.reshape(tensor, [2**N] * 4)
        tensor = bk.transpose(tensor, (0, 2, 1, 3))
        tensor = bk.reshape(tensor, [2] * 4 * N)
        return Channel(tensor, self.qubits)