F biorhythms(birthdate_str, targetdate_str)
   ‘
    Print out biorhythm data for targetdate assuming you were
    born on birthdate.

    birthdate and targetdata are strings in this format:

    YYYY-MM-DD e.g. 1964-12-26
   ’

   print(‘Born: ’birthdate_str‘ Target: ’targetdate_str)

   V birthdate = time:strptime(birthdate_str, ‘%Y-%m-%d’)
   V targetdate = time:strptime(targetdate_str, ‘%Y-%m-%d’)

   V days = (targetdate - birthdate).days()

   print(‘Day: ’days)

   V cycle_labels = [‘Physical’, ‘Emotional’, ‘Mental’]
   V cycle_lengths = [23, 28, 33]
   V quadrants = [(‘up and rising’, ‘peak’), (‘up but falling’, ‘transition’), (‘down and falling’, ‘valley’), (‘down but rising’, ‘transition’)]

   L(i) 3
      V label = cycle_labels[i]
      V length = cycle_lengths[i]
      V position = days % length
      V quadrant = Int(floor((4 * position) / length))
      V percentage = Int(round(100 * sin(2 * math:pi * position / length), 0))
      V transition_date = (targetdate + TimeDelta(days' floor((quadrant + 1) / 4 * length) - position)).strftime(‘%Y-%m-%d’)
      V (trend, next) = quadrants[quadrant]

      String description
      I percentage > 95
         description = ‘peak’
      E I percentage < -95
         description = ‘valley’
      E I abs(percentage) < 5
         description = ‘critical transition’
      E
         description = percentage‘% (’trend‘, next ’next‘ ’transition_date‘)’
      print(label‘ day ’position‘: ’description)

biorhythms(‘2043-03-09’, ‘2072-07-11’)