class_docstr: Class for retrieving different datasets.
class_docstr_tok: ["Class","for","retrieving","different","datasets","."]
code: def num_pitches(self):
      return self.max_pitch + 1 - self.min_pitch
  
imports: import os
  from magenta.models.coconet import lib_mask
  from magenta.models.coconet import lib_pianoroll
  from magenta.models.coconet import lib_util
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 4 for calling the Dataset obj's underlying member method code with example usage: obj.num_pitches() and returns: unknown