+print()
+print(universe.project_out([x]))
+print('sq7 with out constraints involving y and a', sq7.project_out([a, z, x, y])) #drops dims that are passed
+print()
+print('sq1 has {} parameters'.format(sq1.num_parameters()))
+print()
+print('does sq1 constraints involve x?', sq1.involves_dims([x]))