function Range(const Start, Stop, Step: integer): Enumerable<integer>;
begin
  result :=
    YieldingEnumerble<integer>.Create(
      procedure(const Yield: YieldProc<integer>)
      var
        i: integer;
      begin
        i := Start;
        while (i < Stop) do
        begin
          Yield(i);

          i := i + Step;
        end;
      end
    );
end;