code: private boolean remove(List<String> list, String item) {
          if (null != list) {
              if (list.remove(item)) {
                  this.num_items--;
                  return true;
              }
          }
          return false;
      }
docs: Remove the given item from the input list, if present, and update the
  item counter appropriately.
  
  @param list
  @param item
  @return boolean (true means removed)