function groupBy(items: Record<string, any>[], key: string): Record<string, Record<string, any>[]> {
  const groupedItems: Record<string, Record<string, any>[]>= {}
  items.forEach( sourceObject =>{
    const commonKey = sourceObject[key]; 
    if(!groupedItems[commonKey]){
        groupedItems[commonKey] = [sourceObject]
    }else{
        groupedItems[commonKey].push(sourceObject)
    }
  })
  return groupedItems;
}

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