human
Solve the following python programming problem given the following code:
def _wait_for_master(self) : 
    'Wait for master node' 
    def validator() : 
        url = '{server}/_sql'.format (server = self.http_url) 
        resp = self.conn_pool.urlopen ('POST', url, headers = { 
            'Content-Type' : 'application/json', 
}, body = '{"stmt": "select master_node from sys.cluster"}') 
        data = json.loads (resp.data.decode ('utf-8')) 
        if ((resp.status == 200) and data ['rows'] [0] [0]) : 
            sys.stderr.write ('Crate layer started.
') 
            return True 
return False 
self._wait_for (self) 

    
    

    Fix the buggy line: self._wait_for (self)
assistant
#Here is Python program to fix the buggy line: self.

self._wait_for (def validator()