class_docstr: Modify position of the sentence that contains the answer.
class_docstr_tok: ["Modify","position","of","the","sentence","that","contains","the","answer","."]
docstr: Extract the trivial sentence without answers and insert it
      at the beginning or the end.
  :param sample: the sample to transform
  :param kwargs:
  :return: list of sample
docstr_tok: ["Extract","the","trivial","sentence","without","answers","and","insert","it","at","the","beginning","or","the","end",".",":","param","sample",":","the","sample","to","transform",":","param","kwargs",":",":","return",":","list","of","sample"]
code: def _transform(self, sample, **kwargs):
      r"""
      Extract the trivial sentence without answers and insert it
          at the beginning or the end.
      :param sample: the sample to transform
      :param kwargs:
      :return: list of sample
      """
      # filter no-answer samples
      if sample.is_impossible:
          return []
      answers = sample.get_answers()
      sents = sample.get_sentences("context")
      sent_start = 0
      original_idx = -1
      trivial_sent = None
      for idx, sent in enumerate(sents):
          trivial = True
          sent_len = len(self.processor.tokenize(sent))
          for answer in answers:
              if (
                  answer["start"] >= sent_start
                  and answer["end"] <= sent_start + sent_len
              ):
                  trivial = False
                  break
          if trivial:
              sent_span = [sent_start, sent_start + sent_len]
              trivial_sent = sent
              original_idx = idx
              break
      if trivial_sent == " ":
          return []
      if trivial_sent is None:
          return []
      # Insert the sentence at the begin or at the end
      sample = sample.delete_field_at_indices("context", [sent_span])
      if original_idx == 0:
          trans_sample = sample.insert_field_after_index(
              "context",
              len(sample.get_words("context")) - 1,
              trivial_sent,
          )
      else:
          trans_sample = sample.insert_field_before_index(
              "context", 0, trivial_sent
          )
      return [trans_sample]
  
imports: from ..transformation import Transformation
label_desc: Use image node_id 2 for calling the ModifyPos obj's underlying member method code with example usage: obj._transform(sample) and returns: list, list, list, list