code: def test_FracElement_as_expr():
      F, x, y, z = field("x,y,z", ZZ)
      f = (3 * x**2 * y - x * y * z) / (7 * z**3 + 1)
  
      X, Y, Z = F.symbols
      g = (3 * X**2 * Y - X * Y * Z) / (7 * Z**3 + 1)
  
      assert f != g
      assert f.as_expr() == g
  
      X, Y, Z = symbols("x,y,z")
      g = (3 * X**2 * Y - X * Y * Z) / (7 * Z**3 + 1)
  
      assert f != g
      assert f.as_expr(X, Y, Z) == g
  
      raises(ValueError, lambda: f.as_expr(X))
  
imports: from sympy.polys.fields import field, sfield, FracField, FracElement
  from sympy.polys.rings import ring
  from sympy.polys.domains import ZZ, QQ
  from sympy.polys.orderings import lex
  from sympy.testing.pytest import raises, XFAIL
  from sympy.core import symbols, E
  from sympy.core.numbers import Rational
  from sympy.functions.elementary.exponential import exp, log
  from sympy.functions.elementary.miscellaneous import sqrt
label_desc: Use image node_id 7 for calling a global function with example usage: test_FracElement_as_expr() without return types