!7

p {
  assertEqualsVerbose(lithashset('A', 'b', 'k'), charactersAppearingExactlyOnceInEachString(ll("bggkA"));
  assertEqualsVerbose(lithashset('A'), charactersAppearingExactlyOnceInEachString(ll("bggkA", "Abbl"));
  assertEqualsVerbose(lithashset('A', 'B'), charactersAppearingExactlyOnceInEachString(ll("bggkAB", "BAbbl")));
}