docstr: not necessary for large dataset
  it's stupid to return all neg items in super large dataset
docstr_tok: ["not","necessary","for","large","dataset","it","'s","stupid","to","return","all","neg","items","in","super","large","dataset"]
code: def getUserNegItems(self, users):
      """
      not necessary for large dataset
      it's stupid to return all neg items in super large dataset
      """
      raise NotImplementedError
  
imports: import os
  from os.path import join
  import sys
  import paddle
  import numpy
  import pandas
  from paddle.io import Dataset, DataLoader
  from scipy.sparse import csr_matrix
  import scipy.sparse
  from time import time
label_desc: Use image node_id 9 for calling the BasicDataset obj's underlying member method code with example usage: obj.getUserNegItems(users) without return types