code: def exe_cmd(*cmds):
      
      cmd = ' '.join(cmds)
      proc = Popen(cmd, stdout=PIPE, stderr=PIPE, shell=True)
      (out, err) = proc.communicate()
      if not err:
          return out
      return err
docs: Executes commands in a new shell. Directing stderr to PIPE.
  
      This is fastboot's own exe_cmd because of its peculiar way of writing
      non-error info to stderr.
  
      Args:
          cmds: A sequence of commands and arguments.
  
      Returns:
          The output of the command run.
  
      Raises:
          Exception: An error occurred during the command execution.