syntax_data: {"ast_node_type":"other","tokens":[{"end":78,"kind":"keyword","start":0,"text":"Some(other)"}]}
source_snippet:                     Some(other) => self.region_param_expected(data, r, other),
context_before:                     Some(ty::GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt),
context_after:                     None => self.region_param_out_of_range(data, r),