type IDGenerator … type randomIDGenerator … var _ … // NewSpanID returns a non-zero span ID from a randomly-chosen sequence. func (gen *randomIDGenerator) NewSpanID(ctx context.Context, traceID trace.TraceID) trace.SpanID { … } // NewIDs returns a non-zero trace ID and a non-zero span ID from a // randomly-chosen sequence. func (gen *randomIDGenerator) NewIDs(ctx context.Context) (trace.TraceID, trace.SpanID) { … } func defaultIDGenerator() IDGenerator { … }