code: def __init__(self, *datasets):
      keys = set(datasets[0].keys)
      for dataset in datasets[1:]:
          if not len(dataset) == len(datasets[0]):
              raise ValueError("All datasets must have the same length")
          if len(keys.intersection(dataset.keys)) > 0:
              raise ValueError(
                  "All keys must be unique among all datasets"
              )
          keys = keys.union(dataset.keys)
  
      self._datasets = datasets
  
file_path: chainer/chainer/dataset/tabular/_join.py
imports: import six
  from chainer.dataset.tabular import tabular_dataset
label_desc: Use image node_id 1 to create a new _Join object from inherited base classes: tabular_dataset with example: obj = _Join()