How to pass variable from python vk_api function?

Question

Python

Hello, there is a condition under which the bot asks the user for a list of products, and after that it goes into a function that takes a given value and translates them into an array, everything worked, but then I realized that the function that I run starts to work forever, and also in the future I will have to get data from the variable in which this list is written, I could not organize it, and also in the future I will have to use the value of the variable with the products in other functions, how to pass this value and do what I have in mind? The code is below :

Ps-I know that the code is bad enough, because I started to shamanize it and went into a complete dead end and threw off the version of the code in which I came to a dead end

#Добавление списка продуктов в массив
def parser(self):
    for event in longpoll.listen():
      if event.type == VkBotEventType.MESSAGE_NEW:
        if event.obj.text != '':
          if event.from_user :
            a = event.obj.text.split(',')
            print(a)
            vk.messages.send(
              user_id=event.obj.from_id,
              random_id=get_random_id(),
              message="Продукты добавлены в ваш портфель",
              keyboard=keyboard.get_keyboard())

def port(self,a):
  if parser.a !="":
    vk.messages.send(
              user_id=event.obj.from_id,
              random_id=get_random_id(),
              message="Твой портфель состоит из продуктов: \n")
    for i in range(a):
      vk.messages.send(
              user_id=event.obj.from_id,
              random_id=get_random_id(),
              message=a[i]+"\n")
  else:
    vk.messages.send(
            user_id=event.obj.from_id,
            random_id=get_random_id(),
            message="Ваш портфель пуст, добавьте в него продукты:)",
            keyboard=keyboard.get_keyboard())

for event in longpoll.listen():
  if event.type == VkBotEventType.MESSAGE_NEW:
    if event.obj.text != '':
      if event.from_user :
elif event.obj.text == 'Добавить продукты':
          vk.messages.send(
              user_id=event.obj.from_id,
              random_id=get_random_id(),
              message="Введите названия ваших продуктов через запятую.")
          parser()

#---------------------------------------------------------------------------------------------

        elif event.obj.text == 'Мой портфель':
          vk.messages.send(
              user_id=event.obj.from_id,
              random_id=get_random_id(),
              message=port(parser),
              keyboard=keyboard.get_keyboard())