func isDeltaConst(a []int64) bool {
	if len(a) < 2 {
		return false
	}
	d1 := a[1] - a[0]
	prev := a[1]
	for _, next := range a[2:] {
		if next-prev != d1 {
			return false
		}
		prev = next
	}
	return true
}
// isDeltaConst returns true if a contains counter with constant delta.
isDeltaConst returns true if a contains counter with constant delta.
// isDeltaConst returns true if a contains counter with constant delta .
func isDeltaConst(a []int64) bool {
	if len(a) < 2 {
		return false
	}
	d1 := a[1] - a[0]
	prev := a[1]
	for _, next := range a[2:] {
		if next-prev != d1 {
			return false
		}
		prev = next
	}
	return true
}
func isDeltaConst ( a [ ] int64 ) bool { if len ( a ) < 2 { return false } d1 := a [ 1 ] - a [ 0 ] prev := a [ 1 ] for _ , next := range a [ 2 : ] { if next - prev != d1 { return false } prev = next } return true }
isDeltaConst returns true if a contains counter with constant delta.
isDeltaConst returns true if a contains counter with constant delta .