basball question

baseball.py

from functools import reduce

def baseball_game_func(ops):
  res = []
  
  for elm in ops:
    if elm.lstrip('-+').isdigit():
      res.append(int(elm))
    
    elif elm == "+":
      res.append(res[-1] + res[-2])

    elif elm == "D":
      res.append(2 * res[-1])
    
    elif elm == "C":
      res.pop(-1)

  return reduce(lambda x, y: x + y, res) if len(res) > 0 else 0


tests = [
  ["5", "2", "C", "D", "+"],
  ["5", "-2", "4", "C", "D", "9", "+", "+"],
  [""]
]

for test in tests:
  print(baseball_game_func(test))