to go
 setpos pos + vel

 let [:posSum 0]

 let [:temp first (list-of-turtles-at 1 1)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

 let [:temp first (list-of-turtles-at 1 -1)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

 let [:temp first (list-of-turtles-at -1 1)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

 let [:temp first (list-of-turtles-at -1 -1)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

 let [:temp first (list-of-turtles-at -2 0)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]
 
 let [:temp first (list-of-turtles-at 2 0)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

 let [:temp first (list-of-turtles-at 0 2)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

 let [:temp first (list-of-turtles-at 0 -2)]
 let [:temp pos-of :temp]
 let [:posSum :posSum + :temp]

let [:posSum :posSum / (8)]

let [:dPos :posSum - pos]

setvel vel + (spring-const / 100) * :dPos

if pos < 0 [setc yellow]
if pos = 0 [setc red]
if pos > 0 [setc blue]

end