syntax_data: {"ast_node_type":"other","tokens":[{"end":24,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// produces `true`.
context_before:     /// Remove all `Def` nodes, and all branches of the layout for which `f`
context_after:     pub(crate) fn prune<F>(self, f: &F) -> Tree<!, R, T>