//out: the value only goes outward, the
//parameter starts out empty and must
//be assigned inside
procedure GetSum(out Sum: Integer;
  N1, N2: Integer);
begin
  Sum := N1 + N2;
end;

var
  Sum: Integer;
begin
  GetSum(Sum, 5, 3);
  //sum is 8

  WriteLn('sum is ', Sum);
end.