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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def read_value(self, offset=0):
 """ Reads the value of this descriptor. When successful, the value will be returned, otherwise `descriptor_read_value_failed()` of the related device is invoked. """

        try:
            val = self._object.ReadValue(
                {'offset': dbus.UInt16(offset, variant_level=1)},
                dbus_interface='org.bluez.GattDescriptor1')
            return val
        except dbus.exceptions.DBusException as e:
            error = _error_from_dbus_error(e)
            self.service.device.descriptor_read_value_failed(self, error=error)