class_docstr: :class:`UserDataLoader` will return a batch of data which only contains user-id when it is iterated.
  
  Args:
      config (Config): The config of dataloader.
      dataset (Dataset): The dataset of dataloader.
      sampler (Sampler): The sampler of dataloader.
      shuffle (bool, optional): Whether the dataloader will be shuffle after a round. Defaults to ``False``.
  
  Attributes:
      shuffle (bool): Whether the dataloader will be shuffle after a round.
          However, in :class:`UserDataLoader`, it's guaranteed to be ``True``.
code: def collate_fn(self, index):
      index = np.array(index)
      return self.user_list[index]
  
file_path: RecBole/recbole/data/dataloader/user_dataloader.py
imports: import torch
  from logging import getLogger
  from recbole.data.dataloader.abstract_dataloader import AbstractDataLoader
  from recbole.data.interaction import Interaction
  import numpy
label_desc: Use image node_id 3 for calling the UserDataLoader obj's underlying member method code with example usage: obj.collate_fn(index) and returns: self