circles = []

def getColorForWidth(width):
    decColor = (150 - width) // 10
    hexColor = hex(decColor)[2:]
    colorString = '#' + hexColor + hexColor + hexColor
    return colorString

def createCircle(x):
    return Circle(width = 0, height = 0, color = getColorForWidth(0), x = x)

def advanceSingleCircle(circle):
    currentWidth = circle.width
    newWidth = int(currentWidth + 10)
    circle.width = newWidth
    circle.height = newWidth
    circle.color = getColorForWidth(newWidth)

def advanceCircles():
	for circle in circles:
    	advanceSingleCircle(circle)	
    
	if len(circles) > 20: circles.pop(0) # ideally we should destroy the popped circle
        
def animationIteration(i):
    with animation(duration = 0.15):        
        advanceCircles()
    
    circles.append(createCircle(i))
    
circles.append(createCircle(30))
        
for i in range(30):
	advanceCircles()    
	circles.append(createCircle(30))

for i in range(30, 70, 2):
    animationIteration(i)
    
for i in range(15):
    animationIteration(70)
    
for i in range(70, 30, -2):
    animationIteration(i)
    
for i in range(15):
    animationIteration(30)