code: def __init__(self):
      self.original_train_series = None
      self.diffed_train_series = None
      self.first_train_value = None
      self.last_train_value = None
  
file_path: lightwood/lightwood/helpers/ts.py
imports: from typing import Tuple, Dict
  from datetime import datetime
  import numpy
  import pandas
label_desc: Use image node_id 1 to create a new Differencer object  with example: obj = Differencer()