def normalise(coord_paths):
    """
    Take an array of coord, remove any empty paths, and make sure that all the coords
    are tuples not arrays (Which can happen after json.load())
    """
    new_paths = []
    for path in coord_paths:
        if len(path) > 0:
            new_path = []
            for point in path:
                # convert to tuple
                new_path.append((point[0], point[1]))
            new_paths.append(new_path)
            
    return new_paths