code: def _decode_data(self, data):
          
          self.major = data[0]
  
          if data[1] is 0xff:
              self.minor = data[1]
          elif data[1] <= 0x99:
              self.minor = int(data[1:2].tostring().decode('bcd+'))
          else:
              raise DecodingError()
docs: `data` is array.array