def poll_for_activity_task(domain=None, taskList=None, identity=None):
    """
    Used by workers to get an  ActivityTask from the specified activity taskList . This initiates a long poll, where the service holds the HTTP connection open and responds as soon as a task becomes available. The maximum time the service holds on to the request before responding is 60 seconds. If no task is available within 60 seconds, the poll will return an empty result. An empty result, in this context, means that an ActivityTask is returned, but that the value of taskToken is an empty string. If a task is returned, the worker should use its type to identify and process it correctly.
    Access Control
    You can use IAM policies to control this action's access to Amazon SWF resources as follows:
    If the caller does not have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter will be set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows .
    See also: AWS API Documentation
    
    
    :example: response = client.poll_for_activity_task(
        domain='string',
        taskList={
            'name': 'string'
        },
        identity='string'
    )
    
    
    :type domain: string
    :param domain: [REQUIRED]
            The name of the domain that contains the task lists being polled.
            

    :type taskList: dict
    :param taskList: [REQUIRED]
            Specifies the task list to poll for activity tasks.
            The specified string must not start or end with whitespace. It must not contain a : (colon), / (slash), | (vertical bar), or any control characters (u0000-u001f | u007f - u009f). Also, it must not contain the literal string quotarnquot.
            name (string) -- [REQUIRED]The name of the task list.
            

    :type identity: string
    :param identity: Identity of the worker making the request, recorded in the ActivityTaskStarted event in the workflow history. This enables diagnostic tracing when problems arise. The form of this identity is user defined.

    :rtype: dict
    :return: {
        'taskToken': 'string',
        'activityId': 'string',
        'startedEventId': 123,
        'workflowExecution': {
            'workflowId': 'string',
            'runId': 'string'
        },
        'activityType': {
            'name': 'string',
            'version': 'string'
        },
        'input': 'string'
    }
    
    
    :returns: 
    domain (string) -- [REQUIRED]
    The name of the domain that contains the task lists being polled.
    
    taskList (dict) -- [REQUIRED]
    Specifies the task list to poll for activity tasks.
    The specified string must not start or end with whitespace. It must not contain a : (colon), / (slash), | (vertical bar), or any control characters (u0000-u001f | u007f - u009f). Also, it must not contain the literal string quotarnquot.
    
    name (string) -- [REQUIRED]The name of the task list.
    
    
    
    identity (string) -- Identity of the worker making the request, recorded in the ActivityTaskStarted event in the workflow history. This enables diagnostic tracing when problems arise. The form of this identity is user defined.
    
    """
    pass
