old_contents: #!/usr/bin/env python
  # encoding: utf-8
  
  """
  .. codeauthor:: Tsuyoshi Hombashi <tsuyoshi.hombashi@gmail.com>
  """
  
  from __future__ import absolute_import
  from __future__ import print_function
  
  import errno
  import sys
  
  import logbook
  import subprocrunner
  
  from ._argparse_wrapper import ArgparseWrapper
  from ._common import (
      check_tc_command_installation,
      initialize,
      is_execute_tc_command,
      verify_network_interface,
      write_tc_script,
  )
  from ._const import (
      VERSION,
      Tc,
      TcCommandOutput,
  )
  from ._error import NetworkInterfaceNotFoundError
  from ._logger import (
      LOG_FORMAT_STRING,
      logger,
      set_logger,
      set_log_level,
  )
  from .traffic_control import TrafficControl
  
  
  logbook.StderrHandler(
      level=logbook.DEBUG, format_string=LOG_FORMAT_STRING).push_application()
  
  
  def parse_option():
      parser = ArgparseWrapper(VERSION)
  
      group = parser.parser.add_argument_group("Traffic Control")
      group.add_argument(
          "-d", "--device", required=True,
          help="network device name (e.g. eth0)")
  
      return parser.parser.parse_args()
  
  
  def main():
      options = parse_option()
  
      initialize(options)
  
      if is_execute_tc_command(options.tc_command_output):
          check_tc_command_installation()
      else:
          subprocrunner.SubprocessRunner.default_is_dry_run = True
          set_logger(False)
  
      try:
          verify_network_interface(options.device)
      except NetworkInterfaceNotFoundError as e:
          logger.error(e)
          return errno.EINVAL
  
      subprocrunner.SubprocessRunner.clear_history()
  
      tc = TrafficControl(options.device)
      if options.log_level == logbook.INFO:
          subprocrunner.set_log_level(logbook.ERROR)
  
      try:
          return_code = tc.delete_all_tc()
      except NetworkInterfaceNotFoundError as e:
          logger.debug(e)
          return 0
  
      command_history = "\n".join(tc.get_command_history())
  
      if options.tc_command_output == TcCommandOutput.STDOUT:
          print(command_history)
          return return_code
  
      if options.tc_command_output == TcCommandOutput.SCRIPT:
          set_logger(True)
          write_tc_script(
              Tc.Command.TCDEL, command_history, filename_suffix=options.device)
          return return_code
  
      logger.debug("command history\n{}".format(command_history))
  
      return return_code
  
  
  if __name__ == '__main__':
      sys.exit(main())
  
new_contents: #!/usr/bin/env python
  # encoding: utf-8
  
  """
  .. codeauthor:: Tsuyoshi Hombashi <tsuyoshi.hombashi@gmail.com>
  """
  
  from __future__ import absolute_import
  from __future__ import print_function
  
  import errno
  import sys
  
  import logbook
  import subprocrunner
  
  from ._argparse_wrapper import ArgparseWrapper
  from ._common import (
      check_tc_command_installation,
      initialize,
      is_execute_tc_command,
      verify_network_interface,
      write_tc_script,
  )
  from ._const import (
      VERSION,
      Tc,
      TcCommandOutput,
  )
  from ._error import NetworkInterfaceNotFoundError
  from ._logger import (
      LOG_FORMAT_STRING,
      logger,
      set_logger,
      set_log_level,
  )
  from .traffic_control import TrafficControl
  
  
  logbook.StderrHandler(
      level=logbook.DEBUG, format_string=LOG_FORMAT_STRING).push_application()
  
  
  def parse_option():
      parser = ArgparseWrapper(VERSION)
  
      group = parser.parser.add_argument_group("Traffic Control")
      group.add_argument(
          "-d", "--device", required=True,
          help="network device name (e.g. eth0)")
  
      return parser.parser.parse_args()
  
  
  def main():
      options = parse_option()
  
      initialize(options)
  
      if is_execute_tc_command(options.tc_command_output):
          check_tc_command_installation()
      else:
          subprocrunner.SubprocessRunner.default_is_dry_run = True
          set_logger(False)
  
      try:
          verify_network_interface(options.device)
      except NetworkInterfaceNotFoundError as e:
          logger.error(e)
          return errno.EINVAL
  
      subprocrunner.SubprocessRunner.clear_history()
  
      tc = TrafficControl(options.device)
      if options.log_level == logbook.INFO:
          subprocrunner.set_log_level(logbook.ERROR)
  
      return_code = tc.delete_all_tc()
  
      command_history = "\n".join(tc.get_command_history())
  
      if options.tc_command_output == TcCommandOutput.STDOUT:
          print(command_history)
          return return_code
  
      if options.tc_command_output == TcCommandOutput.SCRIPT:
          set_logger(True)
          write_tc_script(
              Tc.Command.TCDEL, command_history, filename_suffix=options.device)
          return return_code
  
      logger.debug("command history\n{}".format(command_history))
  
      return return_code
  
  
  if __name__ == '__main__':
      sys.exit(main())
  
subject: Remove an error handling that never reach