new_contents: class Solution(object):
      def multiply(self, num1, num2):
          """
          :type num1: str
          :type num2: str
          :rtype: str
          """
          if num1 == '0' or num2 == '0':
              return '0'
          res = [0] * (len(num1) + len(num2))
          for j in xrange(len(num2)):
              for i in xrange(len(num1)):
                  t = int(num1[- i - 1]) * int(num2[- j - 1])
                  res[i + j] += t
                  
          for k in xrange(len(res) - 1):
              res[k + 1] += res[k] / 10
              res[k] %= 10
         
          result = ''
          for num in res:
              result = str(num) + result
          return result.lstrip('0')
  
subject: Add MultiplyStrings for leetcode