code: public static <K> NumberMap<K, Float> newFloatMap() {
  		return new NumberMap<K, Float>() {
  			@Override
  			public void add(K key, Float addend) {
  				put(key, containsKey(key) ? (get(key) + addend) : addend);
  			}
  			@Override
  			public void sub(K key, Float subtrahend) {
  				put(key, (containsKey(key) ? get(key) : 0f) - subtrahend);
  			}
  		};
  	}
docs: Creates a NumberMap for Floats.
  
  @param <K>
  @return NumberMap&lt;K, Float&gt;