code: def prime_factors(n):
      
      i = 2
      while i <= sqrt(n):
          if n % i == 0:
              l = prime_factors(n/i)
              l.append(i)
              return l
          i += 1
      return [n]
docs: Lists prime factors of a given natural integer, from greatest to smallest
      :param n: Natural integer
      :rtype : list of all prime factors of the given natural n