_colors = [Color.white, Color(255,240,240), Color(255,220,220), Color(255,205,205),
             Color(255,190,190), Color(255,170,170), Color(255,150,150),
             Color(255,130,130), Color(255,110,110), Color(255,45,45),
             Color(255,5,5),Color.magenta]

def forward(i=1):
    if i>1:
      errorMsg("Sorry Dave, I cannot let you use forward with an argument in this exercise. Use a loop instead.")
    else:
      entity.forward()
      c = getGroundColor()
      for i in range(len(_colors)-1):
          if _colors[i] == c:
              if i == len(_colors)-1:
                  c = _colors[i]
              else:
                  c = _colors[i+1]
              break
      setBrushColor(c)    
      brushDown()
      brushUp()
def backward(i=1):
    if i>1:
      errorMsg("Sorry Dave, I cannot let you use backward with an argument in this exercise. Use a loop instead.")
    else:
      errorMsg("Sorry Dave, you cannot run backward like this. Exercising is hard enough -- please don't overplay.")
# BEGIN SOLUTION
for i in range(10):
    for side in range(4):
        for step in range(8):
            forward()
        left()
# END SOLUTION
