{"ast_node_type":"other","tokens":[{"end":13,"kind":"keyword","start":0,"text":"{"}]}
            {
                if fn_ptr_a.sig == fn_ptr_b.sig && fn_ptr_a.num_binders == fn_ptr_b.num_binders =>
                zip_substs(self, None, &fn_ptr_a.substitution.0, &fn_ptr_b.substitution.0)?