syntax_data: {"ast_node_type":"other","tokens":[{"end":84,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //! `SourceMap` and are represented by [`SourceFile`]s. Byte positions are stored in
context_before: //! or various bits of macro expansion) cover a continuous range of bytes in the
context_after: //! [`Span`] and used pervasively in the compiler. They are absolute positions