put 0
put 3
compare function called
  key3, key0
put 6
compare function called
  key6, key3
put 9
compare function called
  key9, key6
put 2
compare function called
  key2, key9
compare function called
  key2, key0
compare function called
  key2, key6
compare function called
  key2, key3
compare function called
  key2, key0
put 5
compare function called
  key5, key3
compare function called
  key5, key9
compare function called
  key5, key6
put 8
compare function called
  key8, key5
compare function called
  key8, key9
compare function called
  key8, key6
put 1
compare function called
  key1, key5
compare function called
  key1, key2
compare function called
  key1, key0
put 4
compare function called
  key4, key5
compare function called
  key4, key2
compare function called
  key4, key3
put 7
compare function called
  key7, key4
compare function called
  key7, key8
compare function called
  key7, key6
