syntax_data: {"ast_node_type":"other","tokens":[{"end":42,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// we track this for debuginfo later.
context_before:     /// The vector of all scopes that we have created thus far;
context_after:     source_scopes: IndexVec<SourceScope, SourceScopeData<'tcx>>,