text: function population(cities) {
      const result = {};
  
      for (city of cities) {
          let tokens = city.split(" <-> ");
          let key = tokens[0];
          let value = Number(tokens[1]);
          
          if (result.hasOwnProperty(key)) {
              value += result[key];
          }
          result[key] = value;
      }
  
      for (let [key, value] of Object.entries(result)) {
          console.log(`${key} : ${value}`)
      }
  }
  
  population(['Istanbul <-> 100000',
  'Honk Kong <-> 2100004',
  'Jerusalem <-> 2352344',
  'Mexico City <-> 23401925',
  'Istanbul <-> 1000']);
  