syntax_data: {"ast_node_type":"other","tokens":[{"end":66,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // knew that `Foo<'x>` (for any 'x) then we also know that
context_before:         // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
context_after:         // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from