You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: datetime.go
    path of file: ./repos/plumber/vendor/github.com/99designs/go-keychain
    
    the code of the file until where you have to start completion: // +build darwin ios

package keychain

/*
#cgo LDFLAGS: -framework CoreFoundation

#include <CoreFoundation/CoreFoundation.h>
*/
import "C"
import (
	"math"
	"time"
)

const nsPerSec = 1000 * 1000 * 1000

// absoluteTimeIntervalSince1970()
    
func unixToAbsoluteTime(s int64, ns int64) C.CFAbsoluteTime {
	// Subtract as int64s first before converting to floating
	// point to minimize precision loss (assuming the given time
	// isn't much earlier than the Core Foundation absolute
	// reference date).
	abs := s - absoluteTimeIntervalSince1970()
	return C.CFAbsoluteTime(abs) + C.CFTimeInterval(ns)/nsPerSec
}