old_contents: #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  #
  
  """
  Authentication is implemented using flask_login and different environments can
  implement their own login mechanisms by providing an `airflow_login` module
  in their PYTHONPATH. airflow_login should be based off the
  `airflow.www.login`
  
  isort:skip_file
  """
  
  # flake8: noqa: F401
  
  import sys
  from typing import Callable, Optional
  
  from airflow import settings
  from airflow import version
  
  __version__ = version.version
  
  __all__ = ['__version__', 'login', 'DAG', 'PY36', 'PY37', 'PY38', 'PY39']
  
  # Make `airflow` an namespace package, supporting installing
  # airflow.providers.* in different locations (i.e. one in site, and one in user
  # lib.)
  __path__ = __import__("pkgutil").extend_path(__path__, __name__)  # type: ignore
  
  settings.initialize()
  
  login: Optional[Callable] = None
  
  PY36 = sys.version_info >= (3, 6)
  PY37 = sys.version_info >= (3, 7)
  PY38 = sys.version_info >= (3, 8)
  PY39 = sys.version_info >= (3, 9)
  
  
  def __getattr__(name):
      # PEP-562: Lazy loaded attributes on python modules
      if name == "DAG":
          from airflow.models.dag import DAG
  
          return DAG
      if name == "AirflowException":
          from airflow.exceptions import AirflowException
  
          return AirflowException
      raise AttributeError(f"module {__name__} has no attribute {name}")
  
  
  if not settings.LAZY_LOAD_PLUGINS:
      from airflow import plugins_manager
  
      plugins_manager.ensure_plugins_loaded()
  
  if not settings.LAZY_LOAD_PROVIDERS:
      from airflow import providers_manager
  
      manager = providers_manager.ProvidersManager()
      manager.initialize_providers_list()
      manager.initialize_providers_hooks()
      manager.initialize_providers_extra_links()
  
  
  # This is never executed, but tricks static analyzers (PyDev, PyCharm,)
  # they contain.
  STATICA_HACK = True
  globals()['kcah_acitats'[::-1].upper()] = False
  if STATICA_HACK:  # pragma: no cover
      from airflow.models.dag import DAG
      from airflow.exceptions import AirflowException
  
  
  if not PY37:
      from pep562 import Pep562
  
      Pep562(__name__)
  
new_contents: #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  #
  
  """
  Authentication is implemented using flask_login and different environments can
  implement their own login mechanisms by providing an `airflow_login` module
  in their PYTHONPATH. airflow_login should be based off the
  `airflow.www.login`
  
  isort:skip_file
  """
  
  # flake8: noqa: F401
  
  import sys
  from typing import Callable, Optional
  
  from airflow import settings
  from airflow import version
  
  __version__ = version.version
  
  __all__ = ['__version__', 'login', 'DAG', 'PY36', 'PY37', 'PY38', 'PY39']
  
  # Make `airflow` an namespace package, supporting installing
  # airflow.providers.* in different locations (i.e. one in site, and one in user
  # lib.)
  __path__ = __import__("pkgutil").extend_path(__path__, __name__)  # type: ignore
  
  settings.initialize()
  
  login: Optional[Callable] = None
  
  PY36 = sys.version_info >= (3, 6)
  PY37 = sys.version_info >= (3, 7)
  PY38 = sys.version_info >= (3, 8)
  PY39 = sys.version_info >= (3, 9)
  
  
  def __getattr__(name):
      # PEP-562: Lazy loaded attributes on python modules
      if name == "DAG":
          from airflow.models.dag import DAG
  
          return DAG
      if name == "AirflowException":
          from airflow.exceptions import AirflowException
  
          return AirflowException
      raise AttributeError(f"module {__name__} has no attribute {name}")
  
  
  if not settings.LAZY_LOAD_PLUGINS:
      from airflow import plugins_manager
  
      plugins_manager.ensure_plugins_loaded()
  
  if not settings.LAZY_LOAD_PROVIDERS:
      from airflow import providers_manager
  
      manager = providers_manager.ProvidersManager()
      manager.initialize_providers_list()
      manager.initialize_providers_hooks()
      manager.initialize_providers_extra_links()
  
  
  # This is never executed, but tricks static analyzers (PyDev, PyCharm,)
  # into knowing the types of these symbols, and what
  # they contain.
  STATICA_HACK = True
  globals()['kcah_acitats'[::-1].upper()] = False
  if STATICA_HACK:  # pragma: no cover
      from airflow.models.dag import DAG
      from airflow.exceptions import AirflowException
  
  
  if not PY37:
      from pep562 import Pep562
  
      Pep562(__name__)
  
subject: Add back deleted comment (#17884)