assignment_statement
    :   _ID
            {
                if( ($$ = lookup_id((char *)$1, GLOBAL_VAR|LOCAL_VAR|PARAMETER)) == -1 )
                    syyerror("invalid lvalue in assignment");
                assign_type = $$;
            }
        numeric _SEMICOLON

    ;

numeric
        :       _ASSIGN num_exp
                {
                        if(!check_types(assign_type, $2))
                                syyerror("incompatible types in assignment");
                }
        |       numeric _ASSIGN num_exp
                {
                        if(!check_types(assign_type, $3))
                                syyerror("incompatible types in assignment");
                }
        ;