Adding Cosinus as utime.sleep variable

[Kreszy]

Okay, so I´m having trouble using the Cosinus as variable for ms. I want Cosinus(x) to reach it´s limit at led 11, then go back down again, so I get a lighting effect like the K.I.T.T from Knight Rider, but i really can`t get it to run. Any suggestions to make my code better in general are also welcome, I´m a bloody beginner.

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import display import leds import utime import color import display import math red=color.Color(255,0, 0) green=color.Color(0, 255, 0) toright=True a=0 b=0 x=math.cos() while True:     leds.set(a, red)     leds.set(b, green)     utime.sleep_ms(x+100)     leds.clear()       if toright==True:         a=a+1         b=a-1     else:         a=a-1         b=a+1     if a==10:         toright=False     if a==0:         toright=True