class type auth_session =An
auth_sessionobject is normally created for every client instance. It contains the current state of authentication. The methods are only interesting for implementors of authentication methods.
This class type might be revised in the future to allow asynchronous
authentication (authentication often uses some network service).
method next_credentials :
t -> string * string * string * string
method server_rejects :
Rpc.server_error -> unit
Rpc_server Rpc_invalid_respto indicate that the returned verifier is wrong.