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: builtin_date.go
    path of file: ./repos/octant/vendor/github.com/dop251/goja
    
    the code of the file until where you have to start completion: package goja

import (
	"fmt"
	"math"
	"time"
)

const (
	maxTime = 8.64e15
)

func timeFromMsec(msec int64) time.Time {
	sec := msec / 1000
	nsec := (msec % 1000) * 1e6
	return time.Unix(sec, nsec)
}

func timeToMsec(t time.Time) 
    
func (r *Runtime) dateproto_setUTCMonth(call FunctionCall) Value {
	obj := r.toObject(call.This)
	if d, ok := obj.self.(*dateObject); ok {
		if d.isSet {
			month := time.Month(int(call.Argument(0).ToInteger()) + 1)
			var day int
			t := d.time.In(time.UTC)
			if len(call.Arguments) > 1 {
				day = int(call.Arguments[1].ToInteger())
			} else {
				day = t.Day()
			}
			d.time = time.Date(t.Year(), month, day, t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC).In(time.Local)
			return intToValue(timeToMsec(d.time))
		} else {
			return _NaN
		}
	}
	r.typeErrorResult(true, "Method Date.prototype.setUTCMonth is called on incompatible receiver")
	panic("Unreachable")
}