public function testUnionAbsorbtion(Set $A, Set $B) { $A∪⟮B∩C⟯ = $A->union($A->intersect($B)); $this->assertEquals($A, $A∪⟮B∩C⟯); $this->assertEquals($A->asArray(), $A∪⟮B∩C⟯->asArray()); }