error: __traverse__ may not take a receiver other than `&self`. Usually, an implementation of `__traverse__(&self, visit: PyVisit<'_>) -> Result<(), PyTraverseError>` should do nothing but calls to `visit.call`. Most importantly, safe access to the GIL is prohibited inside implementations of `__traverse__`, i.e. `Python::with_gil` will panic.
  --> tests/ui/traverse.rs:10:26
   |
10 |     fn __traverse__(slf: PyRef<Self>, visit: PyVisit) -> Result<(), PyTraverseError> {
   |                          ^^^^^

error: __traverse__ may not take a receiver other than `&self`. Usually, an implementation of `__traverse__(&self, visit: PyVisit<'_>) -> Result<(), PyTraverseError>` should do nothing but calls to `visit.call`. Most importantly, safe access to the GIL is prohibited inside implementations of `__traverse__`, i.e. `Python::with_gil` will panic.
  --> tests/ui/traverse.rs:20:26
   |
20 |     fn __traverse__(slf: PyRefMut<Self>, visit: PyVisit) -> Result<(), PyTraverseError> {
   |                          ^^^^^^^^

error: __traverse__ may not take a receiver other than `&self`. Usually, an implementation of `__traverse__(&self, visit: PyVisit<'_>) -> Result<(), PyTraverseError>` should do nothing but calls to `visit.call`. Most importantly, safe access to the GIL is prohibited inside implementations of `__traverse__`, i.e. `Python::with_gil` will panic.
  --> tests/ui/traverse.rs:30:26
   |
30 |     fn __traverse__(slf: Bound<'_, Self>, visit: PyVisit) -> Result<(), PyTraverseError> {
   |                          ^^^^^

error: __traverse__ may not take a receiver other than `&self`. Usually, an implementation of `__traverse__(&self, visit: PyVisit<'_>) -> Result<(), PyTraverseError>` should do nothing but calls to `visit.call`. Most importantly, safe access to the GIL is prohibited inside implementations of `__traverse__`, i.e. `Python::with_gil` will panic.
  --> tests/ui/traverse.rs:40:21
   |
40 |     fn __traverse__(&mut self, visit: PyVisit) -> Result<(), PyTraverseError> {
   |                     ^

error: __traverse__ may not take `Python`. Usually, an implementation of `__traverse__(&self, visit: PyVisit<'_>) -> Result<(), PyTraverseError>` should do nothing but calls to `visit.call`. Most importantly, safe access to the GIL is prohibited inside implementations of `__traverse__`, i.e. `Python::with_gil` will panic.
  --> tests/ui/traverse.rs:60:32
   |
60 |     fn __traverse__(&self, py: Python<'_>, visit: PyVisit<'_>) -> Result<(), PyTraverseError> {
   |                                ^^^^^^^^^^