syntax_data: {"ast_node_type":"other","tokens":[{"end":28,"kind":"keyword","start":0,"text":"///"}]}
source_snippet: /// ```ignore (illustrative)
context_before: /// instances with the expected upvar types:
context_after: /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {