+universe = Polyhedron([])
+q = sq1 - sq2
+e = Empty
+
+print('sq1 =', sq1) #print correct square
+print('sq2 =', sq2) #print correct square
+print('sq3 =', sq3) #print correct square
+print('sq4 =', sq4) #print correct square
+print('universe =', universe) #print correct square
+print()
+print('¬sq1 =', ~sq1) #test complement
+print()
+print('sq1 + sq1 =', sq1 + sq2) #test addition
+print('sq1 + sq2 =', Polyhedron(sq1 + sq2)) #test addition
+print()
+print('universe + universe =', universe + universe)#test addition
+print('universe - universe =', universe - universe) #test subtraction
+print()
+print('sq2 - sq1 =', sq2 - sq1) #test subtraction
+print('sq2 - sq1 =', Polyhedron(sq2 - sq1)) #test subtraction
+print('sq1 - sq1 =', Polyhedron(sq1 - sq1)) #test subtraction
+print()
+print('sq1 ∩ sq2 =', sq1 & sq2) #test intersection
+print('sq1 ∪ sq2 =', sq1 | sq2) #test union
+print()
+print('sq1 ⊔ sq2 =', Polyhedron(sq1 | sq2)) # test convex union
+print()
+print('check if sq1 and sq2 disjoint:', sq1.isdisjoint(sq2)) #should return false
+print()
+print('sq1 disjoint:', sq1.disjoint()) #make disjoint
+print('sq2 disjoint:', sq2.disjoint()) #make disjoint
+print()
+print('is square 1 universe?:', sq1.isuniverse()) #test if square is universe
+print('is u universe?:', universe.isuniverse()) #test if square is universe