'Returns the eigenstate instance for the passed operators.
This method should be overridden in subclasses. It will handle being
passed either an Operator instance or set of Operator instances. It
should return the corresponding state INSTANCE or simply raise a
NotImplementedError. See cartesian.py for an example.'

@classmethod
def _operators_to_state(self, ops, **options):

    raise NotImplementedError('Cannot    map    operators    to    states    in    this    class.    Method    not    implemented!')
