it's a zigzag line
page1-0.png page6-176.png page7-155.png page2-47.png page1-186.png
page1-186.png page2-21.png page1-0.png page7-155.png page2-189.png page6-153.png page1-116.png page2-47.png page6-176.png page5-157.png
correct.  now it's a large block with reduced corner