code: def set_digital_latch(self, pin, threshold_type, cb):
          
          with self.pymata.data_lock:
              self.digital_latch_table[pin] = [self.LATCH_ARMED, threshold_type, 0, 0, cb]
docs: This method "arms" a pin to allow data latching for the pin.
  
          :param pin: digital pin number
  
          :param threshold_type: DIGITAL_LATCH_HIGH | DIGITAL_LATCH_LOW
  
          :param cb: User provided callback function