code: def fill_concentric_circles(size, center, radius):
      
      for r in range(radius):
          yield concentric_circle(center, r, size=size)
docs: Returns a path that fills a concentric circle with the given radius and center.
      :param radius:
      :param center:
      :param size: The size of the image, used to skip points that are out of bounds.
      :return: Yields iterators, where each iterator yields (x,y) coordinates of points about the circle.
      The path moves outwards from the center of the circle.
      If `size` is specified, points that are out of bounds are skipped.