docs: def _ssacli(*args, **kwargs):
      """Wrapper function for executing hpssacli/ssacli command.
  
      This function executes ssacli command if it exists, else it
      falls back to hpssacli.
      :param args: args to be provided to hpssacli/ssacli command
      :param kwargs: kwargs to be sent to processutils except the
          following:
          - dont_transform_to_hpssa_exception - Set to True if this
            method shouldn't transform other exceptions to hpssa
            exceptions only when hpssa controller is available. This is
            useful when the return code from hpssacli/ssacli is useful for
            analysis.
      :returns: a tuple containing the stdout and stderr after running
          the process.
      :raises: HPSSAOperationError, if some error was encountered and
          dont_dont_transform_to_hpssa_exception was set to False.
      :raises: OSError or processutils.ProcessExecutionError if execution
          failed and dont_transform_to_hpssa_exception was set to True.
      """
  
      dont_transform_to_hpssa_exception = kwargs.get(
          'dont_transform_to_hpssa_exception', False)
      kwargs.pop('dont_transform_to_hpssa_exception', None)
  
      try:
          if os.path.exists("/usr/sbin/ssacli"):
              stdout, stderr = processutils.execute("ssacli",
                                                    *args, **kwargs)
          else:
              stdout, stderr = processutils.execute("hpssacli",
                                                    *args, **kwargs)
      except (OSError, processutils.ProcessExecutionError) as e:
          if 'No controllers detected' in str(e):
              msg = ("SSA controller not found. Enable ssa controller"
                     " to continue with the desired operation")
              raise exception.HPSSAOperationError(reason=msg)
          elif not dont_transform_to_hpssa_exception:
              raise exception.HPSSAOperationError(reason=e)
          else:
              raise
  
      return stdout, stderr