code: def get_previous(i, v_max):
      if i == 0:
          return v_max
      else:
          return i - 1
  
imports: import os
  import pickle
  import random
  import matplotlib.pyplot
  import networkx
  from torch.utils.data import Dataset
label_desc: Use image node_id 1 for calling a global function with example usage: get_previous(i, v_max) and returns: v_max, unknown