function groupByFirstLetter(words: string[]): Record<string, string[]> {

  const map = new Map<string, string[]>()

  words.forEach(word => {
    const key = word.at(0).toLocaleLowerCase()
    const values = map.get(key)

    if (values) {
      map.set(key, [...values, word])
    } else {
      map.set(key, [word])
    }
  })

  return Object.fromEntries(map)
}

// No modificar: necesario para evaluar el resultado.
export { groupByFirstLetter };