from casioplot import *
x,y=200,50
step=1

sens=((0,-1),(-1,0),(0,1),(1,0))
idx_sens = 0


while True:
  x,y=x%380,y%190
  if get_pixel(x,y)[0]:
    idx_sens = (idx_sens+1)%4
    set_pixel(x,y,(0,0,0))
  else:
    set_pixel(x,y,(255,255,255))
    idx_sens = (idx_sens-1)%4

  x=x+sens[idx_sens][0]
  y=y+sens[idx_sens][1]

  show_screen()