code: def spi_bitrate(self):
          
          ret = api.py_aa_spi_bitrate(self.handle, 0)
          _raise_error_if_negative(ret)
          return ret
docs: SPI bitrate in kHz. Not every bitrate is supported by the host
          adapter. Therefore, the actual bitrate may be less than the value which
          is set. The slowest bitrate supported is 125kHz. Any smaller value will
          be rounded up to 125kHz.
  
          The power-on default value is 1000 kHz.