public function ContextWithDuration( $months )
	{
		$durationContexts = $this->DurationContexts();
		$oneDay = new DateInterval("P1D");
		return new ContextsFilter( $instance, array_filter( $durationContexts->getContexts(), function( $context ) use( $months, $oneDay )
		{
			$interval = date_diff(
				new DateTime( $context["period"]["startDate"] ),
				(new DateTime( $context["period"]["endDate"] ))->add( $oneDay ) );

			return $months == ( $interval->m + ( $interval->y * 12 ) );
		} ) );
	}