old_contents: """
  homeassistant.components.binary_sensor.demo
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Demo platform that has two fake binary sensors.
  """
  from homeassistant.components.binary_sensor import BinarySensorDevice
  
  
  def setup_platform(hass, config, add_devices, discovery_info=None):
      """ Sets up the Demo binary sensors. """
      add_devices([
          DemoBinarySensor('Basement Floor Wet', False),
          DemoBinarySensor('Movement Backyard', True),
      ])
  
  
  class DemoBinarySensor(BinarySensorDevice):
      """ A Demo binary sensor. """
  
      def __init__(self, name, state):
          self._name = name
          self._state = state
  
      @property
      def should_poll(self):
          """ No polling needed for a demo binary sensor. """
          return False
  
      @property
      def name(self):
          """ Returns the name of the binary sensor. """
          return self._name
  
      @property
      def is_on(self):
          """ True if the binary sensor is on. """
          return self._state
  
new_contents: """
  homeassistant.components.binary_sensor.demo
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Demo platform that has two fake binary sensors.
  """
  from homeassistant.components.binary_sensor import BinarySensorDevice
  
  
  def setup_platform(hass, config, add_devices, discovery_info=None):
      """ Sets up the Demo binary sensors. """
      add_devices([
          DemoBinarySensor('Basement Floor Wet', False, 'moisture'),
          DemoBinarySensor('Movement Backyard', True, 'motion'),
      ])
  
  
  class DemoBinarySensor(BinarySensorDevice):
      """ A Demo binary sensor. """
  
      def __init__(self, name, state, sensor_class):
          self._name = name
          self._state = state
          self._sensor_type = sensor_class
  
      @property
      def sensor_class(self):
          """ Return our class. """
          return self._sensor_type
  
      @property
      def should_poll(self):
          """ No polling needed for a demo binary sensor. """
          return False
  
      @property
      def name(self):
          """ Returns the name of the binary sensor. """
          return self._name
  
      @property
      def is_on(self):
          """ True if the binary sensor is on. """
          return self._state
  
subject: Update the sensor classes in the demo binary_sensor