old_contents: # Make marshmallow's functions and classes importable from flask-io
  from marshmallow import pre_load, pre_dump, post_load, post_dump, Schema, ValidationError, validates_schema
  from marshmallow.utils import missing
  
  from .api import WebAPI
  from .decorators import authenticator, permissions, content_negotiator, renderer, serializer, route
  from .views import ViewBase
  
  
new_contents: # Make marshmallow's functions and classes importable from flask-io
  from marshmallow import pre_load, pre_dump, post_load, post_dump, Schema, ValidationError, validates_schema
  from marshmallow.utils import missing
  
  from .api import WebAPI
  from .errors import APIError
  from .decorators import authenticator, permissions, content_negotiator, renderer, serializer, route
  from .views import ViewBase
  
  
subject: Add import for APIError to make it easy to import by users