class_docstr: Coref Sample
class_docstr_tok: ["Coref","Sample"]
docstr: For the given word idx, determine which sen it is in.
  
  :param int idx: word idx
  :return int: sen_idx, which sentence is word idx in
docstr_tok: ["For","the","given","word","idx",",","determine","which","sen","it","is","in",".",":","param","int","idx",":","word","idx",":","return","int",":","sen_idx",",","which","sentence","is","word","idx","in"]
code: def index_in_sen(self, idx):
      r"""
      For the given word idx, determine which sen it is in.
  
      :param int idx: word idx
      :return int: sen_idx, which sentence is word idx in
  
      """
      return self.eqlen_sen_map()[idx]
  
imports: from ....common.settings import ORIGIN, TASK_MASK
  from ....common.utils.fp_utils import *
  from ....common.utils.shift_utils import *
  from .sample import Sample
  from ..field import ListField, TextField
label_desc: Use image node_id 11 for calling the CorefSample obj's underlying member method code with example usage: obj.index_in_sen(idx) and returns: self