code: def check_valid(op, num):
      try:
          exp = ""
          for i in range(len(op)):
              exp += str(num[i]) + str(op[i])
          exp += str(num[-1])
          exp = str(eval(exp))
      except:
          return False
      return True
  
label_desc: Use image node_id 2 for calling a global function with example usage: check_valid(op, num) and returns: True, False