问RGB cycle python

EN

def shiftColour( colour, level_shift=-1 ):
    """ Return the colour with each component shifted (with boundary looping)"""
    red, green, blue = colour

    red += level_shift     # handle cycling in +/- for any level_shift
    if ( red < 0 ):
        red = 255
    elif ( red > 255 ):
        red = 0

    green += level_shift
    if ( green < 0 ):
        green = 255
    elif ( green > 255 ):
        green = 0

    blue += level_shift
    if ( blue < 0 ):
        blue = 255
    elif ( blue > 255 ):
        blue = 0

    return ( red, green, blue )   # re-combine, back into a colour

### Main
colour = ( 255, 245, 235 )
delta  = 1
for i in range( 300 ):
    colour = shiftColour( colour, delta )
    print("R=%d, G=%d, B=%d" % ( colour[0], colour[1], colour[2] ) )
    if ( i % 50 == 0 ):
        delta *= -1
        print( "direction-change" )

RGB = (255,200,201)

red = RGB[0]
green = RGB[1]
blue = RGB[2]

step = -1

for i in range( max(RGB) * 2 + 2):

    print(
        "R:",red if red > 0 else 0,
        "G:",green if green > 0 else 0,
        "B:",blue if blue > 0 else 0
        )

    if all( map( lambda x: True if x < 0 else False, [red,green,blue] ) ):
        step = 1

    red += step
    green += step
    blue += step

r = 255
g = 255
b = 255
while(r>0):
    r-=1
    print("Red: %s" %r)
    if(r==0):
        while(g>0):
            g-=1
            print("Green: %s" %g)
            if(g==0):
                while(b>0):
                    b-=1
                    print("Blue: %s" %b)