* The absolute value of the difference between the $time_target and

   * the middle of the guessed semester. Smaller is better.

   */

  $best_score = -1;

  foreach ($semesters as $semester)

    {

      $my_score = abs(($semester['time_end'] + $semester['time_start']) / 2 - $time_target);

      if ($best_score == -1 || $my_score < $best_score)

	{

	  $best_semester = $semester;

	  $best_score = $my_score;

	}

    }

  if (!empty($best_semester))

    return $best_semester;

  return $semester;

}

/**

 * \brief

 *   Return an array of default classes for a particular school.

 *

 * \param $school

 *   The school's handle.