docs: def open(self):
          """Opens a SSH connection with a Pluribus machine."""
          self._connection = paramiko.SSHClient()
          self._connection.set_missing_host_key_policy(paramiko.AutoAddPolicy())
          try:
              self._connection.connect(hostname=self._hostname,
                                       username=self._username,
                                       password=self._password,
                                       timeout=self._timeout,
                                       port=self._port)
              self._connection.get_transport().set_keepalive(self._keepalive)
              self.connected = True
              self.config = PluribusConfig(self)
          except paramiko.ssh_exception.AuthenticationException:
              raise pyPluribus.exceptions.ConnectionError("Unable to open connection with {hostname}: \
                  invalid credentials!".format(hostname=self._hostname))
          except socket_error as sockerr:
              raise pyPluribus.exceptions.ConnectionError("Cannot open connection: {skterr}. \
                  Wrong port?".format(skterr=sockerr.message))
          except socket_gaierror as sockgai:
              raise pyPluribus.exceptions.ConnectionError("Cannot open connection: {gaierr}. \
                  Wrong hostname?".format(gaierr=sockgai.message))