def describe_vtl_devices(GatewayARN=None, VTLDeviceARNs=None, Marker=None,
    Limit=None):
    """
    Returns a description of virtual tape library (VTL) devices for the specified tape gateway. In the response, AWS Storage Gateway returns VTL device information.
    This operation is only supported in the tape gateway architecture.
    See also: AWS API Documentation
    
    Examples
    Returns a description of virtual tape library (VTL) devices for the specified gateway.
    Expected Output:
    
    :example: response = client.describe_vtl_devices(
        GatewayARN='string',
        VTLDeviceARNs=[
            'string',
        ],
        Marker='string',
        Limit=123
    )
    
    
    :type GatewayARN: string
    :param GatewayARN: [REQUIRED]
            The Amazon Resource Name (ARN) of the gateway. Use the ListGateways operation to return a list of gateways for your account and region.
            

    :type VTLDeviceARNs: list
    :param VTLDeviceARNs: An array of strings, where each string represents the Amazon Resource Name (ARN) of a VTL device.
            Note
            All of the specified VTL devices must be from the same gateway. If no VTL devices are specified, the result will contain all devices on the specified gateway.
            (string) --
            

    :type Marker: string
    :param Marker: An opaque string that indicates the position at which to begin describing the VTL devices.

    :type Limit: integer
    :param Limit: Specifies that the number of VTL devices described be limited to the specified number.

    :rtype: dict
    :return: {
        'GatewayARN': 'string',
        'VTLDevices': [
            {
                'VTLDeviceARN': 'string',
                'VTLDeviceType': 'string',
                'VTLDeviceVendor': 'string',
                'VTLDeviceProductIdentifier': 'string',
                'DeviceiSCSIAttributes': {
                    'TargetARN': 'string',
                    'NetworkInterfaceId': 'string',
                    'NetworkInterfacePort': 123,
                    'ChapEnabled': True|False
                }
            },
        ],
        'Marker': 'string'
    }
    
    
    """
    pass
