class_docstr: subword_nmt: official BPE subword transform class.
code: def _parse_opts(self):
      super()._parse_opts()
      self.dropout = {
          "src": self.src_subword_alpha,
          "tgt": self.tgt_subword_alpha,
      }
  
imports: import re
  from onmt.utils.logging import logger
  from onmt.transforms import register_transform
  from .transform import Transform, ObservableStats
  from onmt.constants import DefaultTokens
label_desc: Use image node_id 2 for calling the BPETransform obj's underlying member method code with example usage: obj._parse_opts() without return types