syntax_data: {"ast_node_type":"variable","tokens":[{"end":91,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                     let mut cause = traits::ObligationCause::misc(self.span, self.body_id);
context_before:                 .map(|(i, term)| {
context_after:                     // The first arg is the self ty - use the correct span for it.