code: def gen_masked_source_target(self, tokens, vocab: Vocabulary):
      dec_source: List[int] = [vocab.get_mask_index() for idx in tokens]
      dec_target = self._prepare_dec_target(dec_source, tokens, vocab)
      return dec_source, dec_target
  
imports: from typing import Dict, List, Optional, Set
  import numpy
  from pytext.common.constants import SpecialTokens, Token
  from pytext.config.component import Component, ComponentType
  from pytext.config.pytext_config import ConfigBase
  from pytext.data.data_structures.annotation import Annotation, Intent, Root, Slot
  from pytext.data.utils import VocabBuilder, Vocabulary
label_desc: Use image node_id 2 for calling the MaskEverything obj's underlying member method code with example usage: obj.gen_masked_source_target(tokens, vocab) and returns: dec_source,  dec_target