Process a pair of VSGI.Request and VSGI.Response.
It is passed to a VSGI.Server in order to receive request to process.
| req |
a resource being requested |
| res |
the response to that request |
|
'true' if the request has been or will eventually be handled, otherwise 'false' |
| Error |
unrecoverable error condition can be raised and will be handled by the implementation |