[Header 1 ("",[],[]) [Str "A",Space,Str "Test",Space,Str "of",Space,Str "Headers"]
,Header 2 ("",[],[]) [Str "Second",Space,Str "Level"]
,Para [Str "Some",Space,Str "plain",Space,Str "text."]
,Header 3 ("",[],[]) [Str "Third",Space,Str "level"]
,Para [Str "Some",Space,Str "more",Space,Str "plain",Space,Str "text."]]