syntax_data: {"ast_node_type":"impl","tokens":[{"end":85,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     ///     // This uses the impl from the standard library to prove `Vec<T>: Clone`.
context_before:     ///     let x: Vec<u32> = Vec::new();
context_after:     ///     let y = x.clone();