“u#” should not be deprecated without first deprecating “u”, which is less useful due to not returning a buffer length.

Also, I have always been mystified about how “s#”, “z#”, “y” and “y#” can properly to return a pointer into a buffer for arbitrary immutable bytes-like objects, without requiring PyBuffer_Release() to be called. Perhaps this is bad design to be discouraged. Or maybe a documentation oversight somewhere.