sp_x, sp_y = sympy.symbols('x y')
self.assertEqual(Expression.fromsympy(sp_x), self.x)
self.assertEqual(Expression.fromsympy(sympy.Rational(22, 7)), self.pi)
sp_x, sp_y = sympy.symbols('x y')
self.assertEqual(Expression.fromsympy(sp_x), self.x)
self.assertEqual(Expression.fromsympy(sympy.Rational(22, 7)), self.pi)