syntax_data: {"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// a function pointer that has the shape `for<'env> fn() -> (&'env T, ...)`.
context_before:     pub tupled_upvars_ty: I::Ty,
context_after:     /// This allows us to represent the binder of the self-captures of the closure.