helper function for null test . throws an interal_error exception if its parameter is null . concode_field_sep Integer hashcode_cache concode_elem_sep HashMap<lalr_item,lalr_item> _all concode_field_sep lalr_item add concode_elem_sep void add concode_elem_sep boolean is_superset_of concode_elem_sep void remove concode_elem_sep void remove concode_elem_sep Iterator<lalr_item> iterator concode_elem_sep boolean contains concode_elem_sep int size concode_elem_sep lalr_item find concode_elem_sep int hashCode concode_elem_sep lalr_item get_one concode_elem_sep boolean equals concode_elem_sep boolean equals concode_elem_sep boolean is_subset_of concode_elem_sep void compute_closure concode_elem_sep String toString