function secondsInYear( value ) {
	var yr;
	if ( arguments.length ) {
		if ( isDateObject( value ) ) {
			yr = value.getFullYear();
		} else if ( isInteger( value ) ) {
			yr = value;
		} else {
			throw new TypeError( format( 'invalid argument. Must provide either an integer or a Date object. Value: `%s`.', value ) );
		}
	} else {
		// Note: cannot cache as application could cross over into a new year:
		yr = currentYear();
	}
	if ( isLeapYear( yr ) ) {
		return LEAP_YEAR;
	}
	return NON_LEAP_YEAR;
}
Returns the number of seconds in a year.

@param {(integer|Date)} value - year or `Date` object
@throws {TypeError} must provide either an integer or a `Date` object
@returns {integer} number of seconds in a year

@example
var num = secondsInYear();
// returns <number>

@example
var num = secondsInYear( 2016 );
// returns 31622400

@example
var num = secondsInYear( 2017 );
// returns 31536000