code: @SuppressWarnings("unchecked")    
      public V remove(Object key) {
  	char k = checkKey(key);
          return remove(k);
      }
docs: Removes the mapping for a key from this map if it is present and returns
  the value to which this map previously associated the key, or {@code
  null} if the map contained no mapping for the key.
  
  @param key key whose mapping is to be removed from the map
  
  @return the previous value associated with key, or {@code null} if there
  was no mapping for key.