code: def find_frets(self, note, maxfret=24):
          
          result = []
          if type(note) == str:
              note = Note(note)
          for x in self.tuning:
              if type(x) == list:
                  base = x[0]
              else:
                  base = x
              diff = base.measure(note)
              if 0 <= diff <= maxfret:
                  result.append(diff)
              else:
                  result.append(None)
          return result
docs: Return a list with for each string the fret on which the note is
          played or None if it can't be played on that particular string.
  
          The maxfret parameter is the highest fret that can be played; note
          should either be a string or a Note object.
  
          Example:
          >>> t = tunings.StringTuning('test', 'test', ['A-3', 'E-4'])
          >>> t.find_frets(Note('C-4')
          [3, None]
          >>> t.find_frets(Note('A-4')
          [12, 5]