pandoc/test/command/shift-heading-level-by.md

```
% pandoc --shift-heading-level-by 1 -t native -s
---
title: My title
...

# First heading

## Second
^D
Pandoc
  ( Meta
    { unMeta = fromList
      [ ( "title", MetaInlines [ Str "My", Space, Str "title" ] ) ]
    }
  )
  [ Header 2
    ( "first-heading", [], [] )
    [ Str "First", Space, Str "heading" ]
  , Header 3
    ( "second", [], [] )
    [ Str "Second" ]
  ]
```

```
% pandoc --shift-heading-level-by -1 -t native -s
---
title: Old title
...

# First heading

## Second

# Another top-level heading
^D
Pandoc
  ( Meta
    { unMeta = fromList
      [ ( "title", MetaInlines [ Str "First", Space, Str "heading" ] ) ]
    }
  )
  [ Header 1
    ( "second", [], [] )
    [ Str "Second" ]
  , Para
    [ Str "Another", Space, Str "top-level", Space, Str "heading" ]
  ]
```