def add_lvp(self, lvp):
        # Only if lvp is not dominated by any other pair, add it.
        for my_lvp in self.LVP_Set.values():
            # If a pair dominates, stop.
            if my_lvp.is_dominant(lvp):
                return False
        # If no pair is dominant, Check if it dominates any other lvp,
        # Remove dominated lvps and add new lvp.
        for my_lvp in list(self.LVP_Set.values()):
            if lvp.is_dominant(my_lvp):
                del self.LVP_Set[my_lvp.get_name()]
        # If no pair is dominant, add lvp to lvs.
        self.LVP_Set.update({lvp.get_name(): copy.deepcopy(lvp)})
        return True

   def merge_with_completions(self, lvs):
        Q = Phi_Environment()
        for my_lvp in lvs.LVP_Set.values():
            is_added = self.add_lvp(my_lvp)
            if is_added:
                for my_choice in my_lvp.get_phi_l().get_choices_list():
                    Q.add_choice(my_lvp.get_phi_l().get_choice(my_choice))

        # while Q isn't empty
        try:
            while Q.get_length_list():
                variable = list(Q.choicesList.values()).pop()
                Q.remove_choice(variable.get_name())
                C = self.find_lvs_completions(variable)
                for pair in C.LVP_Set.values():
                    is_added2 = self.add_lvp(pair)
                    if is_added2:
                        for my_choice2 in pair.get_phi_l().get_choices_list():
                            Q.add_choice(pair.get_phi_l().get_choice(my_choice2))
        except StopIteration:
            return self
        return self