fixed bug in code, when we wrap around to the first point again it should start at key 0
added rounding as we don't need too many decimal places, 4 should be more than enough.
removed the old assignment of `next_point = points[1]`

it wasn't messing with the results of the code as the next statement `next_point = points[0]` was overwriting it, however it shouldn't be there, so goodbye!