boolean function ( ) { return first == null ; }
returns true if this bag is empty . concode_field_sep Node<Item> next concode_elem_sep Item item concode_elem_sep Node<Item> current concode_elem_sep Node<Item> first concode_elem_sep int N concode_field_sep void add concode_elem_sep Item next concode_elem_sep Iterator<Item> iterator concode_elem_sep int size concode_elem_sep boolean hasNext concode_elem_sep void main concode_elem_sep void remove