docs: public static FunctionMap loadFunctionMap() {
          FunctionMap fm = new FunctionMap();
          fm.fm = new HashMap<>();
  
          fm.addFunction("keyMatch", new KeyMatchFunc());
          fm.addFunction("keyMatch2", new KeyMatch2Func());
          fm.addFunction("regexMatch", new RegexMatchFunc());
          fm.addFunction("ipMatch", new IPMatchFunc());
  
          return fm;
      }