docs: def verification_digit(numbers):
          """
          Returns the verification digit for a given numbre.
  
          The verification digit is calculated as follows:
  
          * A = sum of all even-positioned numbers
          * B = A * 3
          * C = sum of all odd-positioned numbers
          * D = B + C
          * The results is the smallset number N, such that (D + N) % 10 == 0
  
          NOTE: Afip's documentation seems to have odd an even mixed up in the
          explanation, but all examples follow the above algorithm.
  
          :param list(int) numbers): The numbers for which the digits is to be
              calculated.
          :return: int
          """
          a = sum(numbers[::2])
          b = a * 3
          c = sum(numbers[1::2])
          d = b + c
          e = d % 10
          if e == 0:
              return e
          return 10 - e