'Create a new initiator group.
Given a list of initiators, create a new initiator group.
:param serial_number: array serial number
:param init_group_name: the name for the initiator group
:param initiator_names: initaitor names
:param extra_specs: the extra specifications
:returns: the initiator group name'

def _create_initiator_group(self, serial_number, init_group_name, initiator_names, extra_specs):

    self.rest.create_initiator_group(serial_number, init_group_name, initiator_names, extra_specs)
    return init_group_name
