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    1 ( "introduction" , [] , [] ) [ Str "Introduction" ]
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    , Str "a"
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    , Str "with"
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    , Str "YAML"
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    , Str "frontmatter."
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    [ Str "First"
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    , Str "paragraph"
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    , Str "with"
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    , Str "some"
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    , Str "content."
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    [ Str "Second"
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    , Str "section"
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    , Str "after"
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    , Str "additional"
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    , Str "metadata."
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, HorizontalRule
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