empty test: ok
nonempty test: ok
empty test after remove: ok

extended paper example test:
size before insert is 0
inserting prio 1, key Lennart2, giving
winner(prio 1, key "Lennart2", maxkey "Lennart2",
  loser_leaf
)
size after insert is 1

size before insert is 1
inserting prio 8, key Warren, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 1, prio 8, key "Warren"
    loser_leaf
  split key "Lennart2"
    loser_leaf
  )
)
size after insert is 2

size before insert is 2
inserting prio 2, key Erik, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 2, prio 8, key "Warren"
    loser_node(size 1, prio 2, key "Erik"
      loser_leaf
    split key "Erik"
      loser_leaf
    )
  split key "Lennart2"
    loser_leaf
  )
)
size after insert is 3

size before insert is 3
inserting prio 7, key Richard, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 3, prio 7, key "Richard"
    loser_node(size 1, prio 2, key "Erik"
      loser_leaf
    split key "Erik"
      loser_leaf
    )
  split key "Lennart2"
    loser_node(size 1, prio 8, key "Warren"
      loser_leaf
    split key "Richard"
      loser_leaf
    )
  )
)
size after insert is 4

size before insert is 4
inserting prio 5, key Simon, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 4, prio 5, key "Simon"
    loser_node(size 1, prio 2, key "Erik"
      loser_leaf
    split key "Erik"
      loser_leaf
    )
  split key "Lennart2"
    loser_node(size 2, prio 7, key "Richard"
      loser_leaf
    split key "Richard"
      loser_node(size 1, prio 8, key "Warren"
        loser_leaf
      split key "Simon"
        loser_leaf
      )
    )
  )
)
size after insert is 5

size before insert is 5
inserting prio 4, key Charles, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 5, prio 5, key "Simon"
    loser_node(size 2, prio 2, key "Erik"
      loser_node(size 1, prio 4, key "Charles"
        loser_leaf
      split key "Charles"
        loser_leaf
      )
    split key "Erik"
      loser_leaf
    )
  split key "Lennart2"
    loser_node(size 2, prio 7, key "Richard"
      loser_leaf
    split key "Richard"
      loser_node(size 1, prio 8, key "Warren"
        loser_leaf
      split key "Simon"
        loser_leaf
      )
    )
  )
)
size after insert is 6

size before insert is 6
inserting prio 6, key Mary, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 6, prio 5, key "Simon"
    loser_node(size 2, prio 2, key "Erik"
      loser_node(size 1, prio 4, key "Charles"
        loser_leaf
      split key "Charles"
        loser_leaf
      )
    split key "Erik"
      loser_leaf
    )
  split key "Lennart2"
    loser_node(size 3, prio 6, key "Mary"
      loser_node(size 1, prio 7, key "Richard"
        loser_leaf
      split key "Mary"
        loser_leaf
      )
    split key "Richard"
      loser_node(size 1, prio 8, key "Warren"
        loser_leaf
      split key "Simon"
        loser_leaf
      )
    )
  )
)
size after insert is 7

size before insert is 7
inserting prio 3, key Phil, giving
winner(prio 1, key "Lennart2", maxkey "Warren",
  loser_node(size 7, prio 3, key "Phil"
    loser_node(size 2, prio 2, key "Erik"
      loser_node(size 1, prio 4, key "Charles"
        loser_leaf
      split key "Charles"
        loser_leaf
      )
    split key "Erik"
      loser_leaf
    )
  split key "Lennart2"
    loser_node(size 4, prio 5, key "Simon"
      loser_node(size 2, prio 6, key "Mary"
        loser_leaf
      split key "Mary"
        loser_node(size 1, prio 7, key "Richard"
          loser_leaf
        split key "Phil"
          loser_leaf
        )
      )
    split key "Richard"
      loser_node(size 1, prio 8, key "Warren"
        loser_leaf
      split key "Simon"
        loser_leaf
      )
    )
  )
)
size after insert is 8

size before insert is 8
inserting prio 1, key Lennart, giving
winner(prio 1, key "Lennart", maxkey "Warren",
  loser_node(size 8, prio 3, key "Phil"
    loser_node(size 3, prio 2, key "Erik"
      loser_node(size 1, prio 4, key "Charles"
        loser_leaf
      split key "Charles"
        loser_leaf
      )
    split key "Erik"
      loser_node(size 1, prio 1, key "Lennart2"
        loser_leaf
      split key "Lennart"
        loser_leaf
      )
    )
  split key "Lennart2"
    loser_node(size 4, prio 5, key "Simon"
      loser_node(size 2, prio 6, key "Mary"
        loser_leaf
      split key "Mary"
        loser_node(size 1, prio 7, key "Richard"
          loser_leaf
        split key "Phil"
          loser_leaf
        )
      )
    split key "Richard"
      loser_node(size 1, prio 8, key "Warren"
        loser_leaf
      split key "Simon"
        loser_leaf
      )
    )
  )
)
size after insert is 9

size before insert is 9
inserting prio 2, key Erik2, giving
winner(prio 1, key "Lennart", maxkey "Warren",
  loser_node(size 9, prio 3, key "Phil"
    loser_node(size 4, prio 2, key "Erik"
      loser_node(size 1, prio 4, key "Charles"
        loser_leaf
      split key "Charles"
        loser_leaf
      )
    split key "Erik"
      loser_node(size 2, prio 1, key "Lennart2"
        loser_node(size 1, prio 2, key "Erik2"
          loser_leaf
        split key "Erik2"
          loser_leaf
        )
      split key "Lennart"
        loser_leaf
      )
    )
  split key "Lennart2"
    loser_node(size 4, prio 5, key "Simon"
      loser_node(size 2, prio 6, key "Mary"
        loser_leaf
      split key "Mary"
        loser_node(size 1, prio 7, key "Richard"
          loser_leaf
        split key "Phil"
          loser_leaf
        )
      )
    split key "Richard"
      loser_node(size 1, prio 8, key "Warren"
        loser_leaf
      split key "Simon"
        loser_leaf
      )
    )
  )
)
size after insert is 10


at_most tests
at_most 0: []
at_most 1: [1 - "Lennart", 1 - "Lennart2"]
at_most 2: [2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2"]
at_most 3: [2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 3 - "Phil"]
at_most 4: [4 - "Charles", 2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 3 - "Phil"]
at_most 5: [4 - "Charles", 2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 3 - "Phil", 5 - "Simon"]
at_most 6: [4 - "Charles", 2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 6 - "Mary", 3 - "Phil", 5 - "Simon"]
at_most 7: [4 - "Charles", 2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 6 - "Mary", 3 - "Phil", 7 - "Richard", 5 - "Simon"]
at_most 8: [4 - "Charles", 2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 6 - "Mary", 3 - "Phil", 7 - "Richard", 5 - "Simon", 8 - "Warren"]
at_most 9: [4 - "Charles", 2 - "Erik", 2 - "Erik2", 1 - "Lennart", 1 - "Lennart2", 6 - "Mary", 3 - "Phil", 7 - "Richard", 5 - "Simon", 8 - "Warren"]

to_ord_assoc_list test:
[1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]

delete tests
delete key Lennart2: prio 1, left [1 - "Lennart", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key Warren: prio 8, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard"]
delete key Erik: prio 2, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key Richard: prio 7, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 8 - "Warren"]
delete key Simon: prio 5, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key Charles: prio 4, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key Mary: prio 6, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 7 - "Richard", 8 - "Warren"]
delete key Phil: prio 3, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key Lennart: prio 1, left [1 - "Lennart2", 2 - "Erik", 2 - "Erik2", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key Erik2: prio 2, left [1 - "Lennart", 1 - "Lennart2", 2 - "Erik", 3 - "Phil", 4 - "Charles", 5 - "Simon", 6 - "Mary", 7 - "Richard", 8 - "Warren"]
delete key NotThere: failed

from_assoc_list test:
via from_assoc_list and via inserts assoc lists agree:
[0 - "M", 1 - "L", 2 - "B", 3 - "N", 4 - "H"]
via from_assoc_list and via inserts psqueues agree:
winner(prio 0, key "M", maxkey "N",
  loser_node(size 4, prio 2, key "B"
    loser_node(size 1, prio 4, key "H"
      loser_leaf
    split key "B"
      loser_leaf
    )
  split key "H"
    loser_node(size 2, prio 1, key "L"
      loser_leaf
    split key "L"
      loser_node(size 1, prio 3, key "N"
        loser_leaf
      split key "M"
        loser_leaf
      )
    )
  )
)


adjust tests on
[0 - "M", 1 - "L", 2 - "B", 3 - "N", 4 - "H"]
adjusting priority of H to 0 succeeded
[0 - "H", 0 - "M", 1 - "L", 2 - "B", 3 - "N"]
adjusting priority of L to 8 succeeded
[0 - "M", 2 - "B", 3 - "N", 4 - "H", 8 - "L"]
adjusting priority of B to 2 succeeded
[0 - "M", 1 - "L", 2 - "B", 3 - "N", 4 - "H"]
adjusting priority of M to 2 succeeded
[1 - "L", 2 - "B", 2 - "M", 3 - "N", 4 - "H"]
adjusting priority of N to 1 succeeded
[0 - "M", 1 - "L", 1 - "N", 2 - "B", 4 - "H"]
adjusting priority of X to 7 failed