human
Solve the following python programming problem given the following code:
def _wait_for_status(self, instances, status, sleep = 3, timeout = 60) : 
    def poll_status(instance) : 
        operation_name = _ ('Wait for {node_process} on {instance} to change status to "{status}"') 
        args = { 
            'node_process' : self.ui_name, 
            'instance' : instance.instance_name, 
            'status' : status.name, 
} 
        return polls.poll (get_status = (lambda : (self.status (instance) == status)), operation_name = operation_name.format (** args), timeout = timeout, sleep = sleep) 
util.execute_on_instances (timeout, poll_status) 

    
    

    Fix the buggy line: util.execute_on_instances (timeout, poll_status)
assistant
#Here is Python code to fix the buggy line: util.

util.execute_on_instances (instances, poll_status)