Electricity price traffic light

[{"id":"tab-price","type":"tab","label":"Electricity price indicator","disabled":false,"info":"Classifies a numeric spot price into three simple bands."},{"id":"inject-price","type":"inject","z":"tab-price","name":"Example: 8.4 c/kWh","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"8.4","payloadType":"num","x":170,"y":100,"wires":[["fn-price"]]},{"id":"fn-price","type":"function","z":"tab-price","name":"Choose colour","func":"const price = Number(msg.payload);\nif (!Number.isFinite(price)) {\n  node.warn('Price was not numeric');\n  return null;\n}\nmsg.price = price;\nmsg.payload = price < 7 ? 'green' : price < 15 ? 'amber' : 'red';\nmsg.topic = 'electricity/price/level';\nreturn msg;","outputs":1,"timeout":0,"noerr":0,"initialize":"","finalize":"","libs":[],"x":420,"y":100,"wires":[["switch-price"]]},{"id":"switch-price","type":"switch","z":"tab-price","name":"Route colour","property":"payload","propertyType":"msg","rules":[{"t":"eq","v":"green","vt":"str"},{"t":"eq","v":"amber","vt":"str"},{"t":"eq","v":"red","vt":"str"}],"checkall":"true","repair":false,"outputs":3,"x":630,"y":100,"wires":[["green-price"],["amber-price"],["red-price"]]},{"id":"green-price","type":"debug","z":"tab-price","name":"Cheap","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":830,"y":60,"wires":[]},{"id":"amber-price","type":"debug","z":"tab-price","name":"Average","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":840,"y":100,"wires":[]},{"id":"red-price","type":"debug","z":"tab-price","name":"Expensive","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","x":850,"y":140,"wires":[]}]