request <peer> <method> <params>
        send a msgpack-rpc request and print a response.
        <params> is a python code snippet, it should be eval'ed to a list.

def do_request(self, line):
        """request <peer> <method> <params>
        send a msgpack-rpc request and print a response.
        <params> is a python code snippet, it should be eval'ed to a list.
        """

        def f(p, method, params):
            result = p.call(method, params)
            print("RESULT %s" % result)

        self._request(line, f)