class_docstr: NSP Reader.
docstr: Add cmdline argurments.
docstr_tok: ["Add","cmdline","argurments","."]
code: def add_cmdline_args(cls, parser):
      """Add cmdline argurments."""
      group = DialogReader.add_cmdline_args(parser)
      group.add_argument(
          "--attention_style",
          type=str,
          default="bidirectional",
          choices=["bidirectional", "unidirectional"],
      )
      group.add_argument(
          "--mix_negative_sample", type=str2bool, default=False
      )
      return group
  
file_path: PaddleHub/modules/text/text_generation/plato2_en_large/readers/nsp_reader.py
imports: from collections import namedtuple
  import numpy
  from .dialog_reader import DialogReader
  from ..utils import pad_batch_data
  from ..utils.args import str2bool
  from ..utils.masking import mask
label_desc: Use image node_id 1 for calling the NSPReader obj's underlying member method code with example usage: obj.add_cmdline_args(cls, parser) and returns: group