code: def __call__(self, dataset: Dataset) -> Dataset:
      self._preprocess(dataset)
      return self._group_all(dataset)
  
file_path: gluonts/src/gluonts/nursery/robust-mts-attack/multivariate/datasets/grouper.py
imports: import logging
  import numpy
  import pandas
  from gluonts.dataset.common import ListDataset, DataEntry, Dataset
label_desc: Use image node_id 2 for calling the Grouper obj's underlying member method code with example usage: obj.__call__(dataset) and returns: self