syntax_data: {"ast_node_type":"other","tokens":[{"end":67,"kind":"keyword","start":0,"text":"positive_impl_span:"}]}
source_snippet:         positive_impl_span: tcx.span_of_impl(positive_impl_def_id),
context_before:         negative_impl_span: tcx.span_of_impl(negative_impl_def_id),
context_after:     });