{"ast_node_type":"variable","tokens":[{"end":97,"kind":"keyword","start":0,"text":"let"}]}
                    let source_projection = ecx.instantiate_binder_with_infer(source_projection);
                .enter(|ecx| -> Result<_, NoSolution> {
                    ecx.eq(self.param_env, source_projection.projection_term, target_projection)?;