procedure
Op (S : in out Set) is
C : Cursor;
B : Boolean;
begin
S.Insert (E); -- can raise CE
S.Insert (E2, C, B); -- conditional
S.Include (E3); -- does not raise CE
C := S.Find (E3);
if Has_Element (C) then -- found
...
end if;
S.Delete (Item => E);
S.Delete (Position => C);
S.Exclude (Item => E2);
end Op;