code: def add_mathml_headers(s):
      return (
          """<math xmlns:mml="http://www.w3.org/1998/Math/MathML"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.w3.org/1998/Math/MathML
          http://www.w3.org/Math/XMLSchema/mathml2/mathml2.xsd">"""
          + s
          + "</math>"
      )
  
imports: from pathlib import Path
  from sympy.utilities.decorator import doctest_depends_on
label_desc: Use image node_id 1 for calling a global function with example usage: add_mathml_headers(s) and returns: unknown