docs: public <T> void link(PushMeasure<T> measure) {
  		if (linkedMeasures.containsKey(measure)) {
  			// already linked
  		} else {
  			MeasureListener<T> listener = new MeasureListener<T>() {
  
  				@Override
  				public void measureGenerated(T value) {
  					increment();
  				}
  			};
  			measure.register(listener);
  			linkedMeasures.put(measure, listener);
  		}
  	}