new_contents: class Solution(object):
      def calPoints(self, ops):
          """
          :type ops: List[str]
          :rtype: int
          """
          s = 0
          stack = []
          for c in ops:
              try:
                  v = int(c)
                  stack.append(v)
              except ValueError:
                  if c == 'C':
                      stack.pop()
                  elif c == 'D':
                      stack.append(stack[-1] * 2)
                  elif c == '+':
                      stack.append(stack[-1] + stack[-2])
          return sum(stack)
  
  
  
subject: Add py solution for 682. Baseball Game