old_contents: # -*- coding: utf-8 -*-
  
  from flask_rest_jsonapi.api import Api
  from flask_rest_jsonapi.resource import ResourceList, ResourceDetail, Relationship
  from flask_rest_jsonapi.data_layers import SqlalchemyDataLayer, MongoDataLayer
  from flask_rest_jsonapi.querystring import QueryStringManager
  from flask_rest_jsonapi.errors import jsonapi_errors_serializer
  
  __all__ = [
      'Api',
      'ResourceList',
      'ResourceDetail',
      'Relationship',
      'SqlalchemyDataLayer',
      'MongoDataLayer',
      'QueryStringManager',
      'jsonapi_errors_serializer'
  ]
  
new_contents: # -*- coding: utf-8 -*-
  
  from flask_rest_jsonapi.api import Api
  from flask_rest_jsonapi.resource import ResourceList, ResourceDetail, Relationship
  from flask_rest_jsonapi.data_layers import SqlalchemyDataLayer
  from flask_rest_jsonapi.querystring import QueryStringManager
  from flask_rest_jsonapi.errors import jsonapi_errors_serializer
  
  __all__ = [
      'Api',
      'ResourceList',
      'ResourceDetail',
      'Relationship',
      'SqlalchemyDataLayer',
      'QueryStringManager',
      'jsonapi_errors_serializer'
  ]
  
subject: remove import of MongoDataLayer because it crash on package import