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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def iterative_encoder_decoder(encoder_input, encoder_self_attention_bias, encoder_decoder_attention_bias, query, hparams):
 """Iterative encoder decoder."""

  for _ in range(hparams.num_rec_steps):
    with tf.variable_scope("step", reuse=tf.AUTO_REUSE):
      encoder_output = image_question_encoder(
          encoder_input,
          encoder_self_attention_bias,
          hparams,
          query)

      decoder_output = decoder(
          query,
          encoder_output,
          None,
          encoder_decoder_attention_bias,
          hparams)

      encoder_input = encoder_output
      query = decoder_output

      return decoder_output