code: def find_installed_packages(self):
          
          list_command = subprocess.Popen(self.list_command, shell=True, stdout=subprocess.PIPE)
          stdout, stderr = list_command.communicate()
          if list_command.returncode != 0:
              raise SystemDependencyError("The command to list the installed system packages failed! ({command})",
                                          command=self.list_command)
          installed_packages = sorted(stdout.decode().split())
          logger.debug("Found %i installed system package(s): %s", len(installed_packages), installed_packages)
          return installed_packages
docs: Find the installed system packages.
  
          :returns: A list of strings with system package names.
          :raises: :exc:`.SystemDependencyError` when the command to list the
                   installed system packages fails.