code: def is_binarized(self):
          
          is_binarized = np.issubdtype(self.pianoroll.dtype, np.bool_)
          return is_binarized
docs: Return True if the pianoroll is already binarized. Otherwise, return
          False.
  
          Returns
          -------
          is_binarized : bool
              True if the pianoroll is already binarized; otherwise, False.