old_contents: import asyncio
  import atexit
  import time
  try:
      import bleak
  except ModuleNotFoundError as error:
      bleak = error
  
  def _wait(coroutine):
      loop = asyncio.get_event_loop()
      return loop.run_until_complete(coroutine)
  
  def sleep(seconds):
      time.sleep(seconds)
  
  class BleakBackend:
      def __init__(self):
          self.connected = set()
          atexit.register(self.stop)
          # run the event loop when sleeping
          global sleep
          sleep = self.pump
      def start(self):
          pass
      def pump(self, seconds=1):
          _wait(asyncio.sleep(seconds))
      def stop(self):
          for device in [*self.connected]:
              device.disconnect()
      def scan(self, timeout=10):
          if isinstance(bleak, ModuleNotFoundError):
              raise bleak
          scanner = bleak.BleakScanner()
          devices = _wait(scanner.discover(timeout))
          return [{'name':device.name, 'address':device.address} for device in devices]
      def connect(self, address):
          result = BleakDevice(self, address)
          result.connect()
          return result
  
  class BleakDevice:
      def __init__(self, adapter, address):
          self._adapter = adapter
          self._client = bleak.BleakClient(address)
      def connect(self):
          _wait(self._client.connect())
          self._adapter.connected.add(self)
      def disconnect(self):
          _wait(self._client.disconnect())
          self._adapter.connected.remove(self)
      # Characteristics have two handles: the declaration handle and the value handle.
      # Pygatt seems to use the value handle, which appears less common.  Bleak uses the
      # declaration handle used by d-bus.
      # With the muse, the declaration and value handles happen to be sequential.
      # So, we subtract 1 to get the declaration handle, and add 1 to get the value handle.
      def char_write_handle(self, value_handle, value, wait_for_response=True, timeout=30):
          declaration_handle = value_handle - 1
          _wait(self._client.write_gatt_char(
              declaration_handle,
              bytearray(value),
              wait_for_response))
      def subscribe(self, uuid, callback=None, indication=False, wait_for_response=True):
          def wrap(declaration_handle, data):
              value_handle = declaration_handle + 1
              callback(value_handle, data)
          _wait(self._client.start_notify(uuid, wrap))
  
new_contents: import asyncio
  import atexit
  import time
  try:
      import bleak
  except ModuleNotFoundError as error:
      bleak = error
  
  def _wait(coroutine):
      loop = asyncio.get_event_loop()
      return loop.run_until_complete(coroutine)
  
  def sleep(seconds):
      time.sleep(seconds)
  
  class BleakBackend:
      def __init__(self):
          self.connected = set()
          atexit.register(self.stop)
          # run the event loop when sleeping
          global sleep
          sleep = self.pump
      def start(self):
          pass
      def pump(self, seconds=1):
          _wait(asyncio.sleep(seconds))
      def stop(self):
          for device in [*self.connected]:
              device.disconnect()
      def scan(self, timeout=10):
          if isinstance(bleak, ModuleNotFoundError):
              raise bleak
          devices = _wait(bleak.BleakScanner.discover(timeout))
          return [{'name':device.name, 'address':device.address} for device in devices]
      def connect(self, address):
          result = BleakDevice(self, address)
          result.connect()
          return result
  
  class BleakDevice:
      def __init__(self, adapter, address):
          self._adapter = adapter
          self._client = bleak.BleakClient(address)
      def connect(self):
          _wait(self._client.connect())
          self._adapter.connected.add(self)
      def disconnect(self):
          _wait(self._client.disconnect())
          self._adapter.connected.remove(self)
      # Characteristics have two handles: the declaration handle and the value handle.
      # Pygatt seems to use the value handle, which appears less common.  Bleak uses the
      # declaration handle used by d-bus.
      # With the muse, the declaration and value handles happen to be sequential.
      # So, we subtract 1 to get the declaration handle, and add 1 to get the value handle.
      def char_write_handle(self, value_handle, value, wait_for_response=True, timeout=30):
          declaration_handle = value_handle - 1
          _wait(self._client.write_gatt_char(
              declaration_handle,
              bytearray(value),
              wait_for_response))
      def subscribe(self, uuid, callback=None, indication=False, wait_for_response=True):
          def wrap(declaration_handle, data):
              value_handle = declaration_handle + 1
              callback(value_handle, data)
          _wait(self._client.start_notify(uuid, wrap))
  
subject: Update backends.py (#181)