Use `CLS_ATTRS` as constant
https://github.com/RustPython/RustPython/pull/3497\#discussion_r791853976
@@ -11,7 +11,7 @@ use std::fmt;
use super::genericalias;
-static CLS_ATTRS: [&str; 1] = ["__module__"];
+const CLS_ATTRS: &[&str] = &["__module__"];
#[pyclass(module = "types", name = "UnionType")]
pub struct PyUnion {
