code: def _connect_stack(self, stack):
          
          try:
              dct = self.parent.call_service(
                  service_name='ansible_mitogen.services.ContextService',
                  method_name='get',
                  stack=mitogen.utils.cast(list(stack)),
              )
          except mitogen.core.CallError:
              LOG.warning('Connection failed; stack configuration was:\n%s',
                          pprint.pformat(stack))
              raise
  
          if dct['msg']:
              if dct['method_name'] in self.become_methods:
                  raise ansible.errors.AnsibleModuleError(dct['msg'])
              raise ansible.errors.AnsibleConnectionFailure(dct['msg'])
  
          self.context = dct['context']
          self.chain = CallChain(self, self.context, pipelined=True)
          if self._play_context.become:
              self.login_context = dct['via']
          else:
              self.login_context = self.context
  
          self.init_child_result = dct['init_child_result']
docs: Pass `stack` to ContextService, requesting a copy of the context object
          representing the last tuple element. If no connection exists yet,
          ContextService will recursively establish it before returning it or
          throwing an error.
  
          See :meth:`ansible_mitogen.services.ContextService.get` docstring for
          description of the returned dictionary.