instruments.go
func (g *Gauge) Snapshot() float64 {
	u := atomic.LoadUint64(&g.value)
	return math.Float64frombits(u)
}
func (g *Gauge) Snapshot() float64 {
	u := atomic.LoadUint64(&g.value)
	return math.Float64frombits(u)
}
func ( g * Gauge ) Snapshot ( ) float64 { u := atomic . LoadUint64 ( & g . value ) return math . Float64frombits ( u ) }
// Snapshot returns the current value.
Snapshot returns the current value .