code: function setAngleCallback(angleFunction){
  
      if (typeof(angleFunction) == 'function'){
  
          gazeCollector.setAngleCallback(angleFunction);
          callbacks.angleCallback = angleFunction;
  
      }
      else
          logger.warn('Trying to set a non function object as angle callback');
      
  }
docs: Sets the function to call when calculating gaze hit point
  @memberof DataCollector
  @param {function} angleFunction