def get_outer_grid(coordinate_list):
    """Get the boundaries of the outer grid for ease of plotting"""
    x_coordinates = list(sorted(i[0] for i in coordinate_list))
    y_coordinates = list(sorted(i[1] for i in coordinate_list))
    min_x = x_coordinates[0] - 2
    max_x = x_coordinates[-1] + 2
    min_y = y_coordinates[0] - 2
    max_y = y_coordinates[-1] + 2
    return ((min_x, min_y), (max_x, max_y))