{P : Sort u} →
  {line : Std.Format} →
    {column : ℕ} →
      {tags : List (ℕ × Std.Format)} →
        {line' : Std.Format} →
          {column' : ℕ} →
            {tags' : List (ℕ × Std.Format)} →
              { line := line, column := column, tags := tags } = { line := line', column := column', tags := tags' } →
                (line = line' → column = column' → tags = tags' → P) → P