code: function (device, charHandle, functionName, errorCallback) {
  			var characteristic = device.charList[charHandle];
  			if (characteristic == null) {
  				var msg = "Could not find the requested characteristic handle '" + charHandle + "'";
  				winble.logger.logError(functionName, msg);
  				errorCallback(msg);
  			}
  			return (characteristic);
  		}
docs: Called internally to look up a previously discovered characteristic by handle. Look up the requested characteristic and complain if we can't find it.