class_docstr: Extracts polyphonic tracks from a quantized NoteSequence.
code: def transform(self, input_object):
      quantized_sequence = input_object
      poly_seqs, stats = polyphony_lib.extract_polyphonic_sequences(
          quantized_sequence,
          min_steps_discard=self._min_steps,
          max_steps_discard=self._max_steps,
      )
      self._set_stats(stats)
      return poly_seqs
  
file_path: magenta/magenta/models/polyphony_rnn/polyphony_rnn_pipeline.py
imports: from magenta.models.polyphony_rnn import polyphony_lib
  from magenta.pipelines import dag_pipeline
  from magenta.pipelines import event_sequence_pipeline
  from magenta.pipelines import note_sequence_pipelines
  from magenta.pipelines import pipeline
  from magenta.pipelines import pipelines_common
  from note_seq.protobuf import music_pb2
label_desc: Use image node_id 2 for calling the PolyphonicSequenceExtractor obj's underlying member method code with example usage: obj.transform(input_object) and returns: poly_seqs