'Gets states from all devices
If `merge_multi_context` is ``True``, returns output of form ``[out1, out2]``.
Otherwise, it returns output of the form
``[[out1_dev1, out1_dev2], [out2_dev1, out2_dev2]]``.
All output elements are `NDArray`.
Parameters
merge_multi_context : bool
Defaults to ``True``. In the case when data-parallelism is used, the states
will be collected from multiple devices. A ``True`` value indicates that we
should merge the collected results so that they look like from a single
executor.
Returns
A list of ``NDArray`` or a list of list of ``NDArray``.'

def get_states(self, merge_multi_context=True):

    assert (self.binded and self.params_initialized)
    assert (not merge_multi_context)
    return []
