syntax_data: {"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// trait are "always applicable". Always applicable means that if
context_before:     /// Specializing on this trait is allowed because all of the impls of this
context_after:     /// `X<'x>: T<'y>` for any lifetimes, then `for<'a, 'b> X<'a>: T<'b>`.