new_contents: class Solution(object):
      def plusOne(self, digits):
          """
          :type digits: List[int]
          :rtype: List[int]
          """
          digits[len(digits)-1] += 1
          if digits[len(digits)-1] < 10:
          	return digits
          for i in xrange(len(digits)-1,0,-1):
          	if digits[i] == 10:
          		digits[i] = 0
          		digits[i-1] += 1
          	else:
          		break
          if digits[0] == 10:
          	digits[0] = 0
          	digits = [1] + digits
          return digits
  
  digits = [0,9,7,9]
  print Solution().plusOne(digits)
  
subject: Add solution for 66 Plus One.