def connect_ssh(self, host, command, username=None, port=None):
        #FIXME: This has no way to deal with passwords..
        args = ['ssh', '-x']
        if port is not None:
            args.extend(['-p', str(port)])
        if username is not None:
            host = "%s@%s" % (username, host)
        args.append(host)
        proc = subprocess.Popen(args + command,
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE)
        return SubprocessWrapper(proc)

# Can be overridden by users
dataset/ETHPy150Open natestedman/Observatory/observatory/lib/dulwich/client.py/SSHVendor.connect_ssh/original