module test_helpers_tests.
  accumulate test_helpers.

  check_exists I J :- I < 4, J < 4.

  check 1 1.
  check 1 2 :- fail.
  check 1 3.
  check 2 1 :- fail.
  check 2 2 :- fail.
  check 2 3 :- fail.
  check 3 1 :- fail.
  check 3 2.
  check 3 3 :- fail.