case MOD: isNumerical = true; break;
case MOD: isNumerical = true; isBoolean = false; break;
	public BinaryExpr ( Expr l, int o, Expr r) {		op = o;		left = l;		right = r;		fib1 = fib2 = null;		switch(op){		 	case ADD:			case SUB:			case MULT:			case DIV:			case MOD: isNumerical = true; break;			case OR :			case AND:			case EQ:			case NE:			case LE:			case GE:			case LT:			case GT: isNumerical = false; isBoolean = true;			default:		}	}