class_docstr: Normalize source and target based on Moses script.
class_docstr_tok: ["Normalize","source","and","target","based","on","Moses","script","."]
docstr: Get opt string of a `corpus`.
docstr_tok: ["Get","opt","string","of","a","`","corpus","`","."]
code: def _get_opt(corpus, opt, def_val):
      """Get opt string of a `corpus`."""
      if "normalize" in corpus["transforms"]:
          value = corpus.get(opt, def_val)
          normalize = value
      else:
          normalize = None
      return normalize
  
imports: from onmt.utils.logging import logger
  import re
  import regex
  from itertools import chain
  from onmt.transforms import register_transform
  from .transform import Transform
label_desc: Use image node_id 4 for calling the NormalizeTransform obj's underlying member method code with example usage: obj._get_opt(corpus, opt, def_val) and returns: normalize