实现设备故障四态状态机

solve()

Fault state machine:
  normal ['fault', 'maintenance', 'normal'] -> normal
  normal ['warning', 'fault', 'maintenance'] -> maintenance
  fault ['normal'] -> normal
Fault dist: {'in_progress': np.int64(2), 'open': np.int64(4), 'resolved': np.int64(9)}