const tracer = promTracer({ client, ns: 'service_name' })
// Will create service_name_tracer_bucket metrics

// Pass a named function
const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms))
const tracedSleep = tracer.trace(sleep)
await tracedSleep(1000)

console.log(await client.register.metrics())
// ...
// service_name_tracer_bucket{le="500",fnName="sleep"} 0
// service_name_tracer_bucket{le="1000",fnName="sleep"} 0
// service_name_tracer_bucket{le="2000",fnName="sleep"} 1
// service_name_tracer_bucket{le="5000",fnName="sleep"} 1
// ...

// Or anonymous function
const nap = tracer.trace('nap', (ms) => new Promise((resolve) => setTimeout(resolve, ms)))
await nap(1000)