code: def from_progression_shorthand(self, shorthand, key='C'):
          
          self.empty()
          chords = progressions.to_chords(shorthand, key)
          # warning Throw error, not a valid shorthand
  
          if chords == []:
              return False
          notes = chords[0]
          self.add_notes(notes)
          return self
docs: Empty the container and add the notes described in the progressions
          shorthand (eg. 'IIm6', 'V7', etc).
  
          See mingus.core.progressions for all the recognized format.
  
          Example:
          >>> NoteContainer().from_progression_shorthand('VI')
          ['A-4', 'C-5', 'E-5']