In the `timing_middleware` example, introspection queries will fail due to `Schema` and others not having `_meta` attributes. API will work and tests pass but introspection will fail, which can be quite confusing to the developer. Simple update makes sure the `root` variable has a `_meta` attribute before accessing it.
"Hash" in the Python world implies a cryptographic hash, or possibly a checksum. Here, I believe "hash" is being used to mean "hash map", which would be more commonly known in Python as a dictionary, or dict for short.
