More examples/features needed

[Fiedzia]

I am trying to implement bindings for some Rust libraries I am using and few things I am missing that would be nice to have examples for:

1. defining class properties
2. default values for parameters - I have no idea how to set them up
3. Subclassing - I'd like to be able to subclass python enum, and don't even know where to start

[fafhrd91]

1. just added properties in this PR #101

2. default values are defined like this:

    def write(&self, data: PyBytes, request_counter: u32 = 0) -> PyResult<PyObject> {
    }

    def write(&self, data: Option<PyBytes> = None) -> PyResult<PyObject> {
    }

[Fiedzia]

Thanks.