pub type ExternalFormatter<'a> = dyn Fn(&str, &str, u32) -> Result<Option<String>> + 'a;Expand description
Formats the contents of an embedded block, like CSS in a style element or
a script body. Receives the language hint (the element’s lang or type
attribute value, or css/js by element kind), the raw inner text, and
the remaining print width. Returning Ok(None) keeps the contents
verbatim.