syntax_data: {"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     //    those specified by the impl/bound. For example, if the obligation
context_before:     // 2. If the output type parameters in the obligation do not match
context_after:     //    is `Vec<Foo>: Iterable<Bar>`, but the impl specifies