def kml_element_name(grid_coords, elem_id="KML"):
    """
    Create a unique element name for KML

    Args:
        grid_coords (GridCoordinate):
        elem_id (str):

    >>> kml_element_name(GridCoordinate(zoom=5, x=42, y=60), elem_id="NL")
    'NL_5_42_60'
    """
    return "_".join(str(x) for x in [elem_id, grid_coords.zoom, grid_coords.x, grid_coords.y])