function groupByRange(numbers: number[], rangeSize: number): Record<string, number[]> {
  const ranges: {[k :string]: number[]} = {}
  numbers.forEach(rangeElement=> {
      const rangeMultiplier =  Math.floor(rangeElement / rangeSize);
      const lowerBound = rangeMultiplier * rangeSize;
      const upperBound = lowerBound + rangeSize;

      const rangeKey = `${lowerBound}-${upperBound}`;
      if (!ranges[rangeKey]){
          ranges[rangeKey] = [rangeElement];
      }else{
          ranges[rangeKey].push(rangeElement)
      }
  })
  console.log(ranges);
  return ranges;
}

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