docs: function checkIfPlaying(){
            runInPage(window.fetaSource.isPlayingStr(),
              function(result){
                  if(!result){
                      setTimeout(checkIfPlaying,500);
                  }else{
                      _window.msgFromDevtools("revertRun",{data: result});
                  }
              },
              function(err){
                alert(errorMessage+"error playing script, line 96.");
              });
          }