old_contents: 
  class MarketoException(Exception):
      message = None
      code = None
      def __init__(self, exc = {'message':None,'code':None}):
          self.message = exc['message']
          self.code = exc['code']
        
      def __str__(self):
          return self.msg, self.code
new_contents: 
  class MarketoException(Exception):
      message = None
      code = None
      def __init__(self, exc = {'message':None,'code':None}):
          self.msg = exc['message']
          self.code = exc['code']
        
      def __str__(self):
          return self.msg, self.code
  
subject: fix key error, self.msg