old_contents: """
  Component to retrieve uptime for Home Assistant.
  
  For more details about this platform, please refer to the documentation at
  https://home-assistant.io/components/sensor.uptime/
  """
  import asyncio
  import logging
  
  import voluptuous as vol
  
  import homeassistant.helpers.config_validation as cv
  import homeassistant.util.dt as dt_util
  from homeassistant.components.sensor import PLATFORM_SCHEMA
  from homeassistant.const import (
      CONF_NAME, CONF_UNIT_OF_MEASUREMENT)
  from homeassistant.helpers.entity import Entity
  
  _LOGGER = logging.getLogger(__name__)
  
  DEFAULT_NAME = 'Uptime'
  
  PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
      vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
      vol.Optional(CONF_UNIT_OF_MEASUREMENT, default='days'):
          vol.All(cv.string, vol.In(['minutes', 'hours', 'days']))
  })
  
  
  @asyncio.coroutine
  def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
      """Set up the uptime sensor platform."""
      name = config.get(CONF_NAME)
      units = config.get(CONF_UNIT_OF_MEASUREMENT)
      async_add_devices([UptimeSensor(name, units)], True)
  
  
  class UptimeSensor(Entity):
      """Representation of an uptime sensor."""
  
      def __init__(self, name, units):
          """Initialize the uptime sensor."""
          self._name = name
          self._icon = 'mdi:clock'
          self._units = units
          self.initial = dt_util.now()
          self._state = None
  
      @property
      def name(self):
          """Return the name of the sensor."""
          return self._name
  
      @property
      def icon(self):
          """Icon to display in the front end."""
          return self._icon
  
      @property
      def unit_of_measurement(self):
          """Return the unit of measurement the value is expressed in."""
          return self._units
  
      @property
      def state(self):
          """Return the state of the sensor."""
          return self._state
  
      @asyncio.coroutine
      def async_update(self):
          """Update the state of the sensor."""
          delta = dt_util.now() - self.initial
          div_factor = 3600
          if self.unit_of_measurement == 'days':
              div_factor *= 24
          elif self.unit_of_measurement == 'minutes':
              div_factor /= 60
          delta = delta.total_seconds() / div_factor
          self._state = round(delta, 2)
          _LOGGER.debug("New value: %s", delta)
  
new_contents: """
  Platform to retrieve uptime for Home Assistant.
  
  For more details about this platform, please refer to the documentation at
  https://home-assistant.io/components/sensor.uptime/
  """
  import logging
  
  import voluptuous as vol
  
  from homeassistant.components.sensor import PLATFORM_SCHEMA
  from homeassistant.const import CONF_NAME, CONF_UNIT_OF_MEASUREMENT
  import homeassistant.helpers.config_validation as cv
  from homeassistant.helpers.entity import Entity
  import homeassistant.util.dt as dt_util
  
  _LOGGER = logging.getLogger(__name__)
  
  DEFAULT_NAME = 'Uptime'
  
  ICON = 'mdi:clock'
  
  PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
      vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
      vol.Optional(CONF_UNIT_OF_MEASUREMENT, default='days'):
          vol.All(cv.string, vol.In(['minutes', 'hours', 'days']))
  })
  
  
  async def async_setup_platform(
          hass, config, async_add_devices, discovery_info=None):
      """Set up the uptime sensor platform."""
      name = config.get(CONF_NAME)
      units = config.get(CONF_UNIT_OF_MEASUREMENT)
  
      async_add_devices([UptimeSensor(name, units)], True)
  
  
  class UptimeSensor(Entity):
      """Representation of an uptime sensor."""
  
      def __init__(self, name, unit):
          """Initialize the uptime sensor."""
          self._name = name
          self._unit = unit
          self.initial = dt_util.now()
          self._state = None
  
      @property
      def name(self):
          """Return the name of the sensor."""
          return self._name
  
      @property
      def icon(self):
          """Icon to display in the front end."""
          return ICON
  
      @property
      def unit_of_measurement(self):
          """Return the unit of measurement the value is expressed in."""
          return self._unit
  
      @property
      def state(self):
          """Return the state of the sensor."""
          return self._state
  
      async def async_update(self):
          """Update the state of the sensor."""
          delta = dt_util.now() - self.initial
          div_factor = 3600
  
          if self.unit_of_measurement == 'days':
              div_factor *= 24
          elif self.unit_of_measurement == 'minutes':
              div_factor /= 60
  
          delta = delta.total_seconds() / div_factor
          self._state = round(delta, 2)
          _LOGGER.debug("New value: %s", delta)
  
subject: Update syntax (#14770)