PStarExpression.Operator operator= getOp(sum);
if (operator == null)
return false;
PStarExpression p= new PostfixExpression();
p.setOperand((Expression) fa1);
p.setOperator(operator);
decl.vbs.remove(vb1);
decl.vbs.remove(vb2);
VariableBinding vb= decl.vbs.get(0);
vb.getParentBlock().replaceChild(p, vb);