syntax_data: {"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //!   `TypeFolder`/`FallibleTypeFolder` when they encounter a type of interest.
context_before: //! - The `TypeFoldable` impls handle most of the traversal, and call into
context_after: //! - A `TypeFolder`/`FallibleTypeFolder` may call into another `TypeFoldable`