class_docstr: Flip every pair of tokens: 1 2 3 4 -> 2 1 4 3.
    
class_docstr_tok: ["Flip","every","pair","of","tokens",":","1","2","3","4","-",">","2","1","4","3","."]
code: def transpose_sequence(self, input_sequence):
      return [
          input_sequence[i + 1] if i % 2 == 0 else input_sequence[i - 1]
          for i in range(len(input_sequence))
      ]
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import random
  from six.moves import range
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.data_generators import text_problems
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
label_desc: Use image node_id 2 for calling the FlipBiGramSequence obj's underlying member method code with example usage: obj.transpose_sequence(input_sequence) and returns: unknown