syntax_data: {"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //! custom visit operations that are specific to the visitor.
context_before: //! This means each visit is a mixture of (a) generic visiting operations, and (b)
context_after: //! - The `TypeVisitable` impls handle most of the traversal, and call into