def layers(nr: int=1, extend: bool=False, toggle: bool=True):
    """Toggle layer(s) visibility 

    :param nr: Number, The layer number to set, zero for all layers 
    :type nr: int
    :param extend: Extend, Add this layer to the current view layers 
    :type extend: bool
    :param toggle: Toggle, Toggle the layer 
    :type toggle: bool
    """
    pass
