question: is the set empty ? concode_field_sep Node[] next concode_elem_sep Node root concode_elem_sep int R concode_elem_sep boolean isString concode_elem_sep int N concode_field_sep void add concode_elem_sep Node add concode_elem_sep boolean contains concode_elem_sep Iterator<String> iterator concode_elem_sep Iterable<String> keysThatMatch concode_elem_sep int size concode_elem_sep Iterable<String> keysWithPrefix concode_elem_sep Node get concode_elem_sep void main concode_elem_sep String longestPrefixOf concode_elem_sep int longestPrefixOf concode_elem_sep void collect concode_elem_sep void collect concode_elem_sep void delete concode_elem_sep Node delete
target: boolean function ( ) { return size ( ) == 0 ; }