how to connect through two or more getwayhost to the targethost and get the sshclient

[caccwin]

self.client = SSHClient()
gate1_session = SSHSession(self.gate1host, jumpusername, password=jumppassword).open()
gate2_session = gate1_session.get_remote_session(self.gate2host, jumpusername, port=port, password=jumppassword)
Target_session = gate2_session.get_remote_session(self.hostname, self.username, password=password)
self.client = Target_session.ssh_client

I try like this but only get null object