class type client_config =object..end
method buckets : Rpc_client.connector arrayi=0..n-1 the array element buckets.(i) contains the
 address of the server storing this bucket. It is allowed to use the
 same server for several buckets.
 This array must be non-empty. If you only use one bucket/one server
 just return a one-element array.
method is_alive : int -> booli. If it returns true the server
        is assumed to be alive. Otherwise, the exception Server_not_alive
        is raised immediately. This feature is useful for checking the
        liveliness of servers proactively, e.g. by pinging them in regular
        intervals.
        If this feature is not needed, just return true for every i
        Implementation restriction: works only for the RPC calls
        get, set, delete, but not for the configuration and statistics
        calls.
method query_timeout : float`Timeout. (-1.0) disabled this feature.method idle_timeout : float