old_contents: """
  urllib3 - Thread-safe connection pooling and re-using.
  """
  from __future__ import absolute_import
  import warnings
  
  from .connectionpool import (
      HTTPConnectionPool,
      HTTPSConnectionPool,
      connection_from_url
  )
  
  from . import exceptions
  from .filepost import encode_multipart_formdata
  from .poolmanager import PoolManager, ProxyManager, proxy_from_url
  from .response import HTTPResponse
  from .util.request import make_headers
  from .util.url import get_host
  from .util.timeout import Timeout
  from .util.retry import Retry
  
  
  # Set default logging handler to avoid "No handler found" warnings.
  import logging
  try:  # Python 2.7+
      from logging import NullHandler
  except ImportError:
      class NullHandler(logging.Handler):
          def emit(self, record):
              pass
  
  __author__ = 'Andrey Petrov (andrey.petrov@shazow.net)'
  __license__ = 'MIT'
  __version__ = 'dev'
  
  __all__ = (
      'HTTPConnectionPool',
      'HTTPSConnectionPool',
      'PoolManager',
      'ProxyManager',
      'HTTPResponse',
      'Retry',
      'Timeout',
      'add_stderr_logger',
      'connection_from_url',
      'disable_warnings',
      'encode_multipart_formdata',
      'get_host',
      'make_headers',
      'proxy_from_url',
  )
  
  logging.getLogger(__name__).addHandler(NullHandler())
  
  
  def add_stderr_logger(level=logging.DEBUG):
      """
      Helper for quickly adding a StreamHandler to the logger. Useful for
      debugging.
  
      Returns the handler after adding it.
      """
      # This method needs to be in this __init__.py to get the __name__ correct
      # even if urllib3 is vendored within another package.
      logger = logging.getLogger(__name__)
      handler = logging.StreamHandler()
      handler.setFormatter(logging.Formatter('%(asctime)s %(levelname)s %(message)s'))
      logger.addHandler(handler)
      logger.setLevel(level)
      logger.debug('Added a stderr logging handler to logger: %s', __name__)
      return handler
  
  # ... Clean up.
  del NullHandler
  
  
  # SecurityWarning's always go off by default.
  warnings.simplefilter('always', exceptions.SecurityWarning, append=True)
  # SubjectAltNameWarning's should go off once per host
  warnings.simplefilter('default', exceptions.SubjectAltNameWarning, append=True)
  # InsecurePlatformWarning's don't vary between requests, so we keep it default.
  warnings.simplefilter('default', exceptions.InsecurePlatformWarning,
                        append=True)
  # SNIMissingWarnings should go off only once.
  warnings.simplefilter('default', exceptions.SNIMissingWarning, append=True)
  
  
  def disable_warnings(category=exceptions.HTTPWarning):
      """
      Helper for quickly disabling all urllib3 warnings.
      """
      warnings.simplefilter('ignore', category)
  
new_contents: """
  urllib3 - Thread-safe connection pooling and re-using.
  """
  from __future__ import absolute_import
  import warnings
  
  from .connectionpool import (
      HTTPConnectionPool,
      HTTPSConnectionPool,
      connection_from_url
  )
  
  from . import exceptions
  from .filepost import encode_multipart_formdata
  from .poolmanager import PoolManager, ProxyManager, proxy_from_url
  from .response import HTTPResponse
  from .util.request import make_headers
  from .util.url import get_host
  from .util.timeout import Timeout
  from .util.retry import Retry
  
  
  # Set default logging handler to avoid "No handler found" warnings.
  import logging
  try:  # Python 2.7+
      from logging import NullHandler
  except ImportError:
      class NullHandler(logging.Handler):
          def emit(self, record):
              pass
  
  __author__ = 'Andrey Petrov (andrey.petrov@shazow.net)'
  __license__ = 'MIT'
  __version__ = 'dev'
  
  __all__ = (
      'HTTPConnectionPool',
      'HTTPSConnectionPool',
      'PoolManager',
      'ProxyManager',
      'HTTPResponse',
      'Retry',
      'Timeout',
      'add_stderr_logger',
      'connection_from_url',
      'disable_warnings',
      'encode_multipart_formdata',
      'get_host',
      'make_headers',
      'proxy_from_url',
  )
  
  logging.getLogger(__name__).addHandler(NullHandler())
  
  
  def add_stderr_logger(level=logging.DEBUG):
      """
      Helper for quickly adding a StreamHandler to the logger. Useful for
      debugging.
  
      Returns the handler after adding it.
      """
      # This method needs to be in this __init__.py to get the __name__ correct
      # even if urllib3 is vendored within another package.
      logger = logging.getLogger(__name__)
      handler = logging.StreamHandler()
      handler.setFormatter(logging.Formatter('%(asctime)s %(levelname)s %(message)s'))
      logger.addHandler(handler)
      logger.setLevel(level)
      logger.debug('Added a stderr logging handler to logger: %s', __name__)
      return handler
  
  # ... Clean up.
  del NullHandler
  
  
  # All warning filters *must* be appended unless you're really certain that they
  # shouldn't be: otherwise, it's very hard for users to use most Python
  # mechanisms to silence them.
  # SecurityWarning's always go off by default.
  warnings.simplefilter('always', exceptions.SecurityWarning, append=True)
  # SubjectAltNameWarning's should go off once per host
  warnings.simplefilter('default', exceptions.SubjectAltNameWarning, append=True)
  # InsecurePlatformWarning's don't vary between requests, so we keep it default.
  warnings.simplefilter('default', exceptions.InsecurePlatformWarning,
                        append=True)
  # SNIMissingWarnings should go off only once.
  warnings.simplefilter('default', exceptions.SNIMissingWarning, append=True)
  
  
  def disable_warnings(category=exceptions.HTTPWarning):
      """
      Helper for quickly disabling all urllib3 warnings.
      """
      warnings.simplefilter('ignore', category)
  
subject: Add an explanatory comment re: append=True