Add support for tags in metrics

Some backend systems like influxdb, datadog, and opentsdb to name a few have support of tags. It would be nice if the library has support of tags built into it. Having tags is super helpful when using query tools like grafana to view you metrics data. I might be coding this out some time in the days to come, would this be a welcome addition to the library? Or does anyone know if this is being worked on or exists somewhere else?