code: def __init__(self, dataset, pad_idx):
      super().__init__(dataset, pad_idx, left_pad=True)
  
file_path: fairseq/fairseq/data/pad_dataset.py
imports: from fairseq.data import data_utils
  from .None import BaseWrapperDataset
label_desc: Use image node_id 1 to create a new LeftPadDataset object from inherited base classes: PadDataset with example: obj = LeftPadDataset(dataset, pad_idx)