old_contents: """Add a setuptools command that runs a helper-based application."""
  try:
      from setuptools import Command
  except ImportError:
      from distutils.core import Command
  
  from . import parser
  from . import platform
  
  
  class RunCommand(Command):
  
      """Run a helper-based application.
  
      This extension is installed as a ``distutils.commands``
      entry point that provides the *run_helper* command.  When
      run, it imports a :class:`helper.Controller` subclass by
      name, creates a new instance, and runs it in the foreground
      until interrupted.  The dotted-name of the controller class
      and an optional configuration file are provided as command
      line parameters.
  
      :param str configuration: the name of a configuration file
          to pass to the application *(optional)*
      :param str controller: the dotted-name of the Python class
          to load and run
  
      """
  
      description = 'run a helper.Controller'
      user_options = [
          ('configuration=', 'c', 'path to application configuration file'),
          ('controller=', 'C', 'controller to run'),
      ]
  
      def initialize_options(self):
          """Initialize parameters."""
          self.configuration = None
          self.controller = None
  
      def finalize_options(self):
          """Required override that does nothing."""
          pass
  
      def run(self):
          """Import the controller and run it.
  
          This mimics the processing done by :func:`helper.start`
          when a controller is run in the foreground.  A new instance
          of ``self.controller`` is created and run until a keyboard
          interrupt occurs or the controller stops on its own accord.
  
          """
          segments = self.controller.split('.')
          controller_class = reduce(getattr, segments[1:],
                                    __import__('.'.join(segments[:-1])))
          cmd_line = ['-f']
          if self.configuration is not None:
              cmd_line.extend(['-c', self.configuration])
          args = parser.get().parse_args(cmd_line)
          controller_instance = controller_class(args, platform)
          try:
              controller_instance.start()
          except KeyboardInterrupt:
              controller_instance.stop()
  
new_contents: """Add a setuptools command that runs a helper-based application."""
  try:
      from setuptools import Command
  except ImportError:
      from distutils.core import Command
  
  try:
      from functools import reduce
  except ImportError:
      pass  # use the builtin for py 2.x
  
  from . import parser
  from . import platform
  
  
  class RunCommand(Command):
  
      """Run a helper-based application.
  
      This extension is installed as a ``distutils.commands``
      entry point that provides the *run_helper* command.  When
      run, it imports a :class:`helper.Controller` subclass by
      name, creates a new instance, and runs it in the foreground
      until interrupted.  The dotted-name of the controller class
      and an optional configuration file are provided as command
      line parameters.
  
      :param str configuration: the name of a configuration file
          to pass to the application *(optional)*
      :param str controller: the dotted-name of the Python class
          to load and run
  
      """
  
      description = 'run a helper.Controller'
      user_options = [
          ('configuration=', 'c', 'path to application configuration file'),
          ('controller=', 'C', 'controller to run'),
      ]
  
      def initialize_options(self):
          """Initialize parameters."""
          self.configuration = None
          self.controller = None
  
      def finalize_options(self):
          """Required override that does nothing."""
          pass
  
      def run(self):
          """Import the controller and run it.
  
          This mimics the processing done by :func:`helper.start`
          when a controller is run in the foreground.  A new instance
          of ``self.controller`` is created and run until a keyboard
          interrupt occurs or the controller stops on its own accord.
  
          """
          segments = self.controller.split('.')
          controller_class = reduce(getattr, segments[1:],
                                    __import__('.'.join(segments[:-1])))
          cmd_line = ['-f']
          if self.configuration is not None:
              cmd_line.extend(['-c', self.configuration])
          args = parser.get().parse_args(cmd_line)
          controller_instance = controller_class(args, platform)
          try:
              controller_instance.start()
          except KeyboardInterrupt:
              controller_instance.stop()
  
subject: Fix usage of ``reduce``.