class_docstr: Series decomposition block
code: def forward(self, x):
      moving_mean = self.moving_avg(x)
      res = x - moving_mean
      return res, moving_mean
  
file_path: BigDL/python/chronos/src/bigdl/chronos/pytorch/model_wrapper/decomposition.py
imports: import torch.nn
  import torch
label_desc: Use image node_id 2 for calling the series_decomp obj's underlying member method code with example usage: obj.forward(x) and returns: res,  moving_mean