code: def test_xxe():
      assert os.path.isfile(path)
      if not lxml:
          skip("lxml not installed.")
  
      mml = dedent(
          rf"""
          <!--?xml version="1.0" ?-->
          <!DOCTYPE replace [<!ENTITY ent SYSTEM "file://{path}"> ]>
          <userInfo>
          <firstName>John</firstName>
          <lastName>&ent;</lastName>
          </userInfo>
          """
      )
      xsl = "mathml/data/simple_mmlctop.xsl"
  
      res = apply_xsl(mml, xsl)
      assert (
          res
          == '<?xml version="1.0"?>\n<userInfo>\n<firstName>John</firstName>\n<lastName/>\n</userInfo>\n'
      )
  
imports: import os
  from textwrap import dedent
  from sympy.external import import_module
  from sympy.testing.pytest import skip
  from sympy.utilities.mathml import apply_xsl
label_desc: Use image node_id 1 for calling a global function with example usage: test_xxe() without return types