syntax_data: {"ast_node_type":"other","tokens":[{"end":37,"kind":"keyword","start":0,"text":".unwrap_or_else(|_|"}]}
source_snippet:                 .unwrap_or_else(|_| {
context_before:             fulfill_implication(infcx, param_env, source_trait_ref, source_impl, target_impl, cause)
context_after:                     bug!(