code: def test_Mul():
      assert precedence(x * y) == PRECEDENCE["Mul"]
      assert precedence(-x * y) == PRECEDENCE["Add"]
  
imports: from sympy.concrete.products import Product
  from sympy.concrete.summations import Sum
  from sympy.core.function import Derivative
  from sympy.core.numbers import Integer, Rational, Float, oo
  from sympy.core.relational import Rel
  from sympy.core.symbol import symbols
  from sympy.functions import sin
  from sympy.integrals.integrals import Integral
  from sympy.series.order import Order
  from sympy.printing.precedence import precedence, PRECEDENCE
label_desc: Use image node_id 5 for calling a global function with example usage: test_Mul() without return types