human
Solve the following python programming problem given the following code:
def converge_chef(self, state_data, api, node_id, **kwargs) : 
    def safe_get_fact(node, fact) : 
        if (not (fact in node ['facts'])) : 
            return None 
return node ['facts'] [fact] 
def verify_facts(node, facts) : 
        for fact in facts : 
            if (not (fact in node ['facts'])) : 
                return False 
return True 
self.logger.info (('Converging node %s via chef-client backend' % (node_id,))) 
    node = api._model_get_by_id ('nodes', node_id) 
    api.apply_expression (node_id, 'attrs.converged := false') 
    if (not ('chef_server_consumed' in node ['facts'])) : 
        return self._fail (msg = 'missing fact: chef_server_consumed') 
chef_server_consumed = node ['facts'] ['chef_server_consumed'] 
    cs = api._model_get_by_id ('nodes', chef_server_consumed) 
    if (not cs) : 
        return self._fail (msg = 'cannot find consumed chef server') 
if (not verify_facts (cs, ['chef_server_uri', 'chef_server_client_name', 'chef_server_client_pem'])) : 
        return self._fail (msg = 'chef server missing chef attrs') 
chef_server_uri = cs ['facts'] ['chef_server_uri'] 
    chef_server_client_name = cs ['facts'] ['chef_server_client_name'] 
    chef_server_client_pem = cs ['facts'] ['chef_server_client_pem'] 
    self.logger.debug ('Creating connection to chef server') 
    pem = StringIO.StringIO (chef_server_client_pem) 
    rsa_key = chef.rsa.Key (pem) 
    chef_api = chef.ChefAPI (chef_server_uri, rsa_key, chef_server_client_name) 
    pem.close () 
    if (not ('chef_environment' in node ['facts'])) : 
        api.apply_expression (node_id, 'facts.backends := remove(facts.backends, "chef-client")') 
        if self._node_exists (nodelist ['name'], chef_api) : 
            chef_node = chef.Node (node ['name'], chef_api) 
            chef_node.delete () 
return self._ok () 
(node_attrs, env_attrs) = self._represent_node_attributes (api, node_id) 
    self.logger.debug (('node: %s' % node_attrs)) 
    self.logger.debug (('environment: %s' % env_attrs)) 
    nova_role =...

    
    

    Fix the buggy line: if self._node_exists (nodelist ['name'], chef_api) :
assistant
#Here is Python code to find consumed chef server') 
.

if self._node_exists (node ['name'], chef_api) :