syntax_data: {"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let generics = self.tcx.generics_of(impl_def_id);
context_before:         let impl_trait_ref = self.tcx.impl_trait_ref(impl_def_id);
context_after:         // We have two cases to worry about here: