returns a string that contains the previous operations performed starting with the initial value of 0 . it uses + , - , , and / to denote the operations that were performed . concode_field_sep int total concode_elem_sep String history concode_field_sep void add concode_elem_sep void subtract concode_elem_sep int getTotal concode_elem_sep void divide concode_elem_sep void multiply
String function ( ) { return history ; }