syntax_data: {"ast_node_type":"other","tokens":[{"end":54,"kind":"keyword","start":0,"text":"ty::UpvarCapture::ByRef(upvar_borrow)"}]}
source_snippet:             ty::UpvarCapture::ByRef(upvar_borrow) => {
context_before:             }
context_after:                 let borrow_kind = match upvar_borrow {