AllRunning returns time ranges relative to the Span's start when any children of the span were running and when any children of the span were blocked on the network.

Running returns time ranges relative to the Span's start when the Span was running, when it was blocked for various reasons, and when it was doing assist work.

A Span describes a single goroutine's contribution of a unit of useful work.

A TreeSummary describes the overall behavior of a tree of Spans.