It will be hard to help you with just the information you have provided. There could be a bug in your python code or an issue with your flow. Please export your flow and attach it to a reply.
In order to make code readable and usable it is necessary to surround your code with three backticks (also known as a left quote or backquote ```)
```
code goes here
```
You can edit and correct your post by clicking the pencil 
icon.
See this post for more details - How to share code or flow json
