prompt: Your task is to convert an English description into an ASCII tree format using this style:
  ```
  packages
   +--pkg-a
   |   `--src
   +--pkg-b
   |   `--src
   `--shared
       `--src
  ```
  
  Convert this description:
  
  flow is a origin directory that groups 2 subdirectories: a and b.
  In the root directory, 'a' includes 1 folders: sub.
  In nested path 'a / sub', The 'sub' collection is vacant.
  Back to the top level.
  At the main level, 'b' hosts 1 contained folders: sub.
  In nested path 'b > sub', Inside 'sub', you'll find it awaits content.
  
  
  Provide your answer wrapped in <ascii_formatted> tags.
verification_info: {"ground_truth": "flow\n +--a\n |   `--sub\n `--b\n     `--sub", "description": "flow is a origin directory that groups 2 subdirectories: a and b.\nIn the root directory, 'a' includes 1 folders: sub.\nIn nested path 'a / sub', The 'sub' collection is vacant.\nBack to the top level.\nAt the main level, 'b' hosts 1 contained folders: sub.\nIn nested path 'b > sub', Inside 'sub', you'll find it awaits content.\n"}