public Object fetchVar(){
        if(left instanceof Operator){
            return ((Operator) left).calculate();
        }
        if(left instanceof Elobj){
            return ((Elobj) left).fetchVal();
        }
        return left;
    }
public Object fetchVar(){
        if(left instanceof Operator){
            return ((Operator) left).calculate();
        }
        if(left instanceof Elobj){
            return ((Elobj) left).fetchVal();
        }
        return left;
    }
public Object fetchVar ( ) { if ( left instanceof Operator ) { return ( ( Operator ) left ) . calculate ( ) ; } if ( left instanceof Elobj ) { return ( ( Elobj ) left ) . fetchVal ( ) ; } return left ; }
取得变得的值
取得变得的值