code: function getCountryList() {
          var countries = grunt.option("countries");
          if (!countries) {
              grunt.fail.fatal("Country list not passed. Example usage: `grunt customBuild --countries=Canada,United States`");
          }
  
          // countries may contain commas in their names. Bit ugly, but simple. This swiches out those escaped commas
          // and replaces them later
          var commaReplaced = countries.replace(/\\,/g, '{COMMA}');
          var targetCountries = _.map(commaReplaced.split(","), function (country) {
              return country.replace(/\{COMMA\}/, ',').trim();
          });
  
          var countryData = [];
          var foundCountryNames = [];
  
          var formattedData = minifyJSON(countriesJSON);
          _.each(formattedData, function (countryInfo) {
              var countryName = countryInfo[0];
              if (_.contains(targetCountries, countryName)) {
                  countryData.push(countryInfo);
                  foundCountryNames.push(countryName);
              }
          });
  
          // if one or more of the countries wasn't found, they probably made a typo: throw a warning but continue
          if (targetCountries.length !== countryData.length) {
              grunt.log.error("The following countries weren't found (check the source/data.json file to ensure you entered the exact country string):");
              var missing = _.difference(targetCountries, foundCountryNames);
              _.each(missing, function (countryName) {
                  grunt.log.error("--", countryName);
              });
  
              // all good! Let the user know what bundle is being created, just to remove any ambiguity
          } else {
              grunt.log.writeln("");
              grunt.log.writeln("Creating bundle with following countries:");
              _.each(targetCountries, function (country) {
                  grunt.log.writeln("* " + country);
              });
          }
  
          config.template.customBuild.options.data.__DATA__ = "\nvar _data = " + JSON.stringify(countryData);
      }
docs: used for the customBuild target. This generates a custom build of CRS with the list of countries specified by the user