old_contents: from .root import Root
  from .base import Base, metadata, db_session
  from .file import File
  from .content import Content, get_content
  
  
  __all__ = [Root, Base, metadata, db_session, File, Content, get_content]
  
new_contents: from .root import Root
  from .base import Base, metadata, db_session
  from .file import File
  from .content import Content, get_content
  
  
  __all__ = [
      Root,
      Base, metadata, db_session,
      File,
      Content, get_content
  ]
  
subject: make future merges easier...