code: def setUp(self):
      self.enc = polyphony_encoder_decoder.PolyphonyOneHotEncoding()
  
file_path: magenta/magenta/models/polyphony_rnn/polyphony_encoder_decoder_test.py
imports: from magenta.models.polyphony_rnn import polyphony_encoder_decoder
  from magenta.models.polyphony_rnn.polyphony_lib import PolyphonicEvent
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling the PolyphonyOneHotEncodingTest obj's underlying member method code with example usage: obj.setUp() without return types