'Merge another KeyedRegion into this KeyedRegion.
:param KeyedRegion other: The other instance to merge with.
:return: None'

def merge(self, other, make_phi_func=None):

    for (_, item) in other._storage.iter_items():
        for loc_and_var in item.objects:
            self.__store(loc_and_var, overwrite=False, make_phi_func=make_phi_func)
    return self
