text: #!/usr/bin/env python3
  
  # Copyright (c) Facebook, Inc. and its affiliates.
  # This source code is licensed under the MIT license found in the
  # LICENSE file in the root directory of this source tree.
  
  from parlai.core.teachers import FbDeprecatedDialogTeacher
  from .build import build
  
  import copy
  import os
  
  
  def _path(opt):
      # Build the data if it doesn't exist.
      build(opt)
      dt = opt['datatype'].split(':')[0]
      return os.path.join(opt['datapath'], 'QACNN', dt + '.txt')
  
  
  class DefaultTeacher(FbDeprecatedDialogTeacher):
      def __init__(self, opt, shared=None):
          opt = copy.deepcopy(opt)
          opt['datafile'] = _path(opt)
          super().__init__(opt, shared)
  