Conditional Union ?

I am using 10g.

Below is a crude example of what I am trying to do

Procedure
( pi_input as interger
)

is

Cursor A
   is
Select 'A' as Letter from Dual;

Cursor B
  is
Select 'A' as Letter from Dual;
   Union
Select 'B' as Letter from Dual;

If pi_input = 1 then
  Open A
Else
  Open B
End If

Notice that Select 'A' as Letter from Dual  is in two cursors. If I
have to make a change to Cursor A, I also have to do it again in
cursor B because "Select 'A' as Letter from Dual' is in two cursors.

Is it possible to eliminate repeat code in the above example? What do
I need to do.