code: def _idx_at_pos(self, pos):
      return self.char_to_idx[self.text[pos]]
  
file_path: pytorch/caffe2/python/examples/char_rnn.py
imports: from caffe2.python import core, workspace, model_helper, utils, brew
  from caffe2.python.rnn_cell import LSTM
  from caffe2.proto import caffe2_pb2
  from caffe2.python.optimizer import build_sgd
  import argparse
  import logging
  import numpy
  from datetime import datetime
label_desc: Use image node_id 3 for calling the CharRNN obj's underlying member method code with example usage: obj._idx_at_pos(pos) and returns: self