code: def add_x10_device(self, housecode, unitcode, feature='OnOff'):
          
          device = insteonplm.devices.create_x10(self, housecode,
                                                 unitcode, feature)
          if device:
              self.devices[device.address.id] = device
          return device
docs: Add an X10 device based on a feature description.
  
          Current features are:
          - OnOff
          - Dimmable
          - Sensor
          - AllUnitsOff
          - AllLightsOn
          - AllLightsOff