The Method class is in charge of interpreting a method configuration. Meaning the Method is concerned with collecting the method lookup, mungers, formatters and executing them on the inputs.
It is the list of the functions that the python method arguments get piped through, that should output a json_rpc ready param dict. Mungers can be validators, normalizers, occur in any order, with probably a huge variation arity, etc. Mungers are kept separate from the request parameter and result formatters, taken from the middleware formatters.
A formatter is a function that takes a value and returns a formatted value. It wraps request function.
Middleware sit between public methods(after all mungers/formatters are applied) and Provider.