DefaultLookupPackage is the default package lookup function, used when [Parser.LookupPackage] is nil.

A Code is a preformatted code block.

A Doc is a parsed Go doc comment.

A DocLink is a link to documentation for a Go package or symbol.

A Heading is a doc comment heading.

A Link is a link to a specific URL.

A LinkDef is a single link definition.

A List is a numbered or bullet list.

A ListItem is a single item in a numbered or bullet list.

A Paragraph is a paragraph of text.

A Parser is a doc comment parser.

A Printer is a doc comment printer.

A Block is block-level content in a doc comment, one of [*Code], [*Heading], [*List], or [*Paragraph].

A Text is text-level content in a doc comment, one of [Plain], [Italic], [*Link], or [*DocLink].

An Italic is a string rendered as italicized text.

A Plain is a string rendered as plain text (not italicized).