static fromSpanContext(spanContext) {
    return new Traceparent({
      traceId: spanContext.traceId,
      parentId: spanContext.spanId,
      // Our span context implementation does not implement the flags as a bit
      // field. So we will just concatenate. See the span implementation in
      // the OTEL bridge code.
      flags: `0${Number(spanContext.traceFlags || 0)}`
    })
  }
Construct a new instance from an OTEL span context.

@link https://opentelemetry.io/docs/concepts/signals/traces/#span-context

@param {object} spanContext

@returns {Traceparent}