{"ast_node_type":"variable","tokens":[{"end":100,"kind":"keyword","start":0,"text":"if"}]}
                        if let ConstraintCategory::CallArgument(Some(call_ty)) = constraint.category
                        // If we find a call in this path, then check if it defines the opaque.
                            && let ty::FnDef(call_def_id, _) = *call_ty.kind()