code: function pathLanguage() {
    var pathlang = (arguments.length < 1) ? null : arguments[0];
    if (pathlang !== 'jsonpath' && pathlang !== 'xpath') {
      throw new Error(
          'pathLanguage takes a path language of xpath or jsonpath'
          );
    }
  
    return {"pathlang": pathlang};
  }
docs: The specification for whether select and context paths use
  XPath or JSONPath as returned by
  the {@link patchBuilder#pathLanguage} function.
  @typedef {object} patchBuilder.PathLanguageParam
  @since 1.0
   
  Specifies whether the language used in context and select paths
  for the document patch is XPath or JSONPath. XPath may be used
  for either JSON or XML documents and is the default path language.
  JSONPath may only be used for JSON documents. A document patch
  cannot contain a mix of XPath and JSONPath.
  @method
  @since 1.0
  @memberof patchBuilder#
  @param {string} language - one of the enumeration xpath|jsonpath
  @returns {patchBuilder.PathLanguageParam} the specification for the path language