syntax_data: {"ast_node_type":"other","tokens":[{"end":78,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// that the `ClosureKind` is actually supported by the coroutine-closure.
context_before:     /// This function expects the upvars to have been computed already, and doesn't check
context_after:     pub fn to_coroutine_given_kind_and_upvars(