error[E0597]: `_pool` does not live long enough
 --> $DIR/static_ref.rs:9:1
  |
9 | #[pymethods]
  | ^^^^^^^^^^^-
  | |          |
  | |          `_pool` dropped here while still borrowed
  | borrowed value does not live long enough
  | cast requires that `_pool` is borrowed for `'static`
  |
  = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)