Function format_openmetrics 

pub fn format_openmetrics(result: &RunResult) -> String

OpenMetrics / Prometheus text exposition for a successful RunResult.

Emits stable gauge names: linkprobe_ok, linkprobe_latency_milliseconds, linkprobe_jitter_milliseconds, linkprobe_download_bits_per_second, linkprobe_upload_bits_per_second, and linkprobe_packet_loss. Only metrics present on the result are written.