Sort an array of 0s, 1s and 2s (LC-0075)

class Solution:
    def sortColors(self, nums):
        lx = 0
        rx = len(nums) - 1
        
        ix = 0
        while ix <= rx:
            if nums[ix] == 0:
                nums[lx], nums[ix] = nums[ix], nums[lx]
                lx = lx + 1
                ix = ix + 1
            elif nums[ix] == 1:
                ix = ix + 1
            else:
                nums[rx], nums[ix] = nums[ix], nums[rx]
                rx = rx - 1