code: def test_symbol_expand():
      x = Symbol("x")
      y = Symbol("y")
  
      f = x**4 * y**4
      assert f == x**4 * y**4
      assert f == f.expand()
  
      g = (x * y) ** 4
      assert g == f
      assert g.expand() == f
      assert g.expand() == g.expand().expand()
  
file_path: sympy/sympy/core/tests/test_eval.py
imports: from sympy.core.function import Function
  from sympy.core.numbers import I, Rational
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol
  from sympy.functions.elementary.exponential import exp
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import cos, tan
  from sympy.testing.pytest import XFAIL
label_desc: Use image node_id 7 for calling a global function with example usage: test_symbol_expand() without return types