{P : Sort u} →
  {str : String} →
    {startPos stopPos : String.Pos.Raw} →
      {str' : String} →
        {startPos' stopPos' : String.Pos.Raw} →
          { str := str, startPos := startPos, stopPos := stopPos } =
              { str := str', startPos := startPos', stopPos := stopPos' } →
            (str = str' → startPos = startPos' → stopPos = stopPos' → P) → P