docs: def missing_host_key(self, client, hostname, key):
          """
          Called when an `.SSHClient` receives a server key for a server that
          isn't in either the system or local `.HostKeys` object.  To accept
          the key, simply return.  To reject, raised an exception (which will
          be passed to the calling application).
          """
          self.host_key = key.get_base64()
          print("Fetched key is: %s" % self.host_key)
          return