error[E0599]: the method `assert_into_py_result` exists for struct `Blah`, but its trait bounds were not satisfied
   --> tests/ui/missing_intopy.rs:3:1
    |
1   | struct Blah;
    | -----------
    | |
    | method `assert_into_py_result` not found for this struct
    | doesn't satisfy `Blah: IntoPy<Py<PyAny>>`
    | doesn't satisfy `Blah: IntoPyResult<Blah>`
2   |
3   | #[pyo3::pyfunction]
    | ^^^^^^^^^^^^^^^^^^^ method cannot be called on `Blah` due to unsatisfied trait bounds
    |
    = note: the following trait bounds were not satisfied:
            `Blah: IntoPy<Py<PyAny>>`
            which is required by `Blah: IntoPyResult<Blah>`
note: the following trait must be implemented
   --> src/conversion.rs
    |
    | pub trait IntoPy<T>: Sized {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: this error originates in the attribute macro `pyo3::pyfunction` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `Blah: IntoPyCallbackOutput<_>` is not satisfied
   --> tests/ui/missing_intopy.rs:3:1
    |
3   | #[pyo3::pyfunction]
    | ^^^^^^^^^^^^^^^^^^^ the trait `IntoPyCallbackOutput<_>` is not implemented for `Blah`
    |
    = help: the following other types implement trait `IntoPyCallbackOutput<Target>`:
              <() as IntoPyCallbackOutput<()>>
              <() as IntoPyCallbackOutput<i32>>
              <*mut PyObject as IntoPyCallbackOutput<*mut PyObject>>
              <HashCallbackOutput as IntoPyCallbackOutput<isize>>
              <IterANextOutput<Py<PyAny>, Py<PyAny>> as IntoPyCallbackOutput<*mut PyObject>>
              <IterANextOutput<T, U> as IntoPyCallbackOutput<IterANextOutput<Py<PyAny>, Py<PyAny>>>>
              <IterNextOutput<Py<PyAny>, Py<PyAny>> as IntoPyCallbackOutput<*mut PyObject>>
              <IterNextOutput<T, U> as IntoPyCallbackOutput<IterNextOutput<Py<PyAny>, Py<PyAny>>>>
            and 7 others
note: required by a bound in `pyo3::callback::convert`
   --> src/callback.rs
    |
    |     T: IntoPyCallbackOutput<U>,
    |        ^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `pyo3::callback::convert`
    = note: this error originates in the attribute macro `pyo3::pyfunction` (in Nightly builds, run with -Z macro-backtrace for more info)