question: returns a string represntation of this stack . concode_field_sep ArrayList stack concode_elem_sep int height concode_field_sep Expr pop concode_elem_sep void set concode_elem_sep Expr pop1 concode_elem_sep int size concode_elem_sep Expr[] pop2 concode_elem_sep Expr get concode_elem_sep boolean isEmpty concode_elem_sep void replace concode_elem_sep void push concode_elem_sep Expr peek concode_elem_sep Expr peek concode_elem_sep int height
target: String function ( ) { return stack . toString ( ) ; }