A running track in code

You will write functions for the two edges and the area of a running track. Then you will check the stagger rule and count squares to test an area.

The idea. The inner edge is $2L + 2\pi r$. The outer edge is longer by $2\pi w$. The area is two straight strips plus a ring.

Your tasks.

1. In lap, return the length of the edge of a track with straight sides length and end radius radius, rounded to $4$ decimals.
2. In track_area, return the area of a track of width width whose inner edge has the end radius radius, rounded to $4$ decimals.
3. In stagger, return the difference in length between the outer edge and the inner edge, rounded to $4$ decimals, using only width.
4. Set longest_lane to the name of the lane in lanes that has the longest edge. A lane is described by its end radius.