def write(self, buf, start=0, end=None):
         if not buf:
 
     def write(self, buf, start=0, end=None):
         if not buf:
             self._spi.max_speed_hz = self.baudrate
             self._spi.mode = self.mode
             self._spi.bits_per_word = self.bits
             self._spi.max_speed_hz = self.baudrate
             self._spi.mode = self.mode
             self._spi.bits_per_word = self.bits
             self._spi.close()
         except FileNotFoundError as not_found:
             print("Could not open SPI device - check if SPI is enabled in kernel!")
             raise
 
             self._spi.close()
         except FileNotFoundError as not_found:
             print("Could not open SPI device - check if SPI is enabled in kernel!")
             raise
 
-    def readinto(self, buf, start=0, end=None):
+    def readinto(self, buf, start=0, end=None, write_value=0):
             self._spi.max_speed_hz = self.baudrate
             self._spi.mode = self.mode
             self._spi.bits_per_word = self.bits
             self._spi.max_speed_hz = self.baudrate
             self._spi.mode = self.mode
             self._spi.bits_per_word = self.bits
         if in_end is None:
             in_end = len(buffer_in)
         if out_end - out_start != in_end - in_start:
             raise RuntimeError('Buffer slices must be of equal length.')
         try:
             self._spi.open(self._port, 0)
         if in_end is None:
             in_end = len(buffer_in)
         if out_end - out_start != in_end - in_start:
             raise RuntimeError('Buffer slices must be of equal length.')
         try:
             self._spi.open(self._port, 0)
             self._spi.max_speed_hz = self.baudrate
             self._spi.mode = self.mode
             self._spi.bits_per_word = self.bits
             self._spi.max_speed_hz = self.baudrate
             self._spi.mode = self.mode
             self._spi.bits_per_word = self.bits