code: def ping(self):
          
          self._idle()
          self._transaction_start()
          self._i2c_start()
          self._i2c_write_bytes([self._address_byte(False)])
          self._i2c_stop()
          response = self._transaction_end()
          if len(response) != 1:
              raise RuntimeError('Expected 1 response byte but received {0} byte(s).'.format(len(response)))
          return ((response[0] & 0x01) == 0x00)
docs: Attempt to detect if a device at this address is present on the I2C
          bus.  Will send out the device's address for writing and verify an ACK
          is received.  Returns true if the ACK is received, and false if not.