syntax_data: {"ast_node_type":"other","tokens":[{"end":56,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //! - source code as represented by a [`SourceMap`]; and
context_before: //! - the *span*, represented by [`SpanData`] and related types;
context_after: //! - interned strings, represented by [`Symbol`]s, with some common symbols available statically