syntax_data: {"ast_node_type":"other","tokens":[{"end":67,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// we convert the principal trait-ref into a normal trait-ref,
context_before:     /// Object types don't have a self type specified. Therefore, when
context_after:     /// you must give *some* self type. A common choice is `mk_err()`