def wire(self):
        """
        Returns (Register, int) tuple where the int is the index of
        the wire else None
        """
        if self.data_dict['type'] not in ['in', 'out']:
            raise QiskitError('The node %s is not an input/output node' % str(self))
        return self.data_dict.get('wire')
Returns (Register, int) tuple where the int is the index of
        the wire else None