export function topNWords(text: string, n: number): string[] {
  let freq = {}
  text.toLowerCase().split(' ').forEach( (word) => {
    if (!freq[word]) {
    freq[word] = 0;
  }
  freq[word]++
  })
  return Object.entries(freq).slice(0, n).flat().filter((v) => typeof v === 'string');
}