code: def remove_sentence_boundaries(tensor, mask):
      """
      Remove begin/end of sentence embeddings from the batch of sentences.
      Given a batch of sentences with size ``(batch_size, timesteps, dim)``
      this returns a tensor of shape ``(batch_size, timesteps - 2, dim)`` after removing
      the beginning and end sentence markers.  The sentences are assumed to be padded on the right,
      with the beginning of each sentence assumed to occur at index 0 (i.e., ``mask[:, 0]`` is assumed
      to be 1).
  
      Returns both the new tensor and updated mask.
  
      This function is the inverse of ``add_sentence_boundary_token_ids``.
  
      Parameters
      ----------
      tensor : ``torch.Tensor``
          A tensor of shape ``(batch_size, timesteps, dim)``
      mask : ``torch.Tensor``
           A tensor of shape ``(batch_size, timesteps)``
  
      Returns
      -------
      tensor_without_boundary_tokens : ``torch.Tensor``
          The tensor after removing the boundary tokens of shape ``(batch_size, timesteps - 2, dim)``
      new_mask : ``torch.Tensor``
          The new mask for the tensor of shape ``(batch_size, timesteps - 2)``.
      """
      # TODO: matthewp, profile this transfer
      sequence_lengths = mask.sum(dim=1).detach().cpu().numpy()
      tensor_shape = list(tensor.data.shape)
      new_shape = list(tensor_shape)
      new_shape[1] = tensor_shape[1] - 2
      tensor_without_boundary_tokens = tensor.new_zeros(*new_shape)
      new_mask = tensor.new_zeros(
          (new_shape[0], new_shape[1]), dtype=torch.long
      )
      for i, j in enumerate(sequence_lengths):
          if j > 2:
              tensor_without_boundary_tokens[i, : (j - 2), :] = tensor[
                  i, 1 : (j - 1), :
              ]
              new_mask[i, : (j - 2)] = 1
  
      return tensor_without_boundary_tokens, new_mask
  
imports: from __future__ import division
  from __future__ import absolute_import
  from collections import defaultdict
  import logging
  import math
  import torch
  from allennlp.common.checks import ConfigurationError
label_desc: Use image node_id 32 for calling a global function with example usage: remove_sentence_boundaries(tensor, mask) and returns: tensor_without_boundary_tokens,  new_mask