code: public static MutableComboBoxModel leftShift(MutableComboBoxModel self, Object i) {
          self.addElement(i);
          return self;
      }
docs: Overloads the left shift operator to provide an easy way to add
  items to a MutableComboBoxModel.
  
  @param self a MutableComboBoxModel
  @param i    an item to be added to the model.
  @return same model, after the value was added to it.
  @since 1.6.4