code: public V remove(Object key) {
          V retval=get(key);
          try {
              MethodCall call=new MethodCall(REMOVE, key);
              disp.callRemoteMethods(null, call, call_options);
          }
          catch(Exception e) {
              throw new RuntimeException("remove(" + key + ") failed", e);
          }
          return retval;
      }
docs: Removes the key (and its corresponding value) from this map. This method
  does nothing if the key is not in the map.
  
  @param key
  the key that needs to be removed
  @return the previous value associated with <tt>key</tt>, or
  <tt>null</tt> if there was no mapping for <tt>key</tt>
  @throws NullPointerException
  if the specified key is null