---+ More exercises

  1. Write a variation of the map/1 predicate that takes two dates, and
  that shows on a map all piracy events that happened in the
  time-interval between those two dates. You will have to use the
  predicate parse_time/3 convert between dates and the
  internal representation of timestamps as a number. Example:
  http://localhost:3020/map?start=2008-01-01&end=2008-12-31 (showing all
  piracy events in the year 2008)

  2. Write a variation of the map/1 predicate that takes a type of ship
  and shows on a map all piracy events with that type of ship involved.
  Example: http://localhost:3020/map?type=atype_passenger_vessel Make
  sure that you take the hierarchy of ship-types into account when
  calculating your answer. Of course you can use the code you wrote for
  exercise 2 of [[Pack your queries in Prolog
  predicates][PiratePredicates.txt]].

  You can use the predicate [[rdf_global_id/2][</help/source/doc_for?object=rdf_global_id/2>]] to translate =atype_passenger_vessel= into a proper resource.