export function wordFactorial(words: string[]): Set<string> {
  const combinations: Set<string> = new Set([]);
  for (let i = 0; i < words.length; i++) {
    let inner = "";
    for (let ii = i; ii < words.length; ii++) {
      inner += (ii > i ? " " : "") + words[ii].toLowerCase();
      combinations.add(inner);
    }
  }
  return combinations;
}