code: def get_placeholders(hparams):
      return dict(
          pianorolls=tf.placeholder(
              tf.float32,
              [
                  None,
                  None,
                  hparams.num_pitches,
                  hparams.num_instruments,
              ],
          ),
          masks=tf.placeholder(
              tf.float32,
              [
                  None,
                  None,
                  hparams.num_pitches,
                  hparams.num_instruments,
              ],
          ),
          lengths=tf.placeholder(tf.float32, [None]),
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import os
  from magenta.models.coconet import lib_hparams
  from magenta.models.coconet import lib_tfutil
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling a global function with example usage: get_placeholders(hparams) and returns: dict