code: function tryAddingExtensions(candidate, extensions, failedLookupLocation, onlyRecordFailures, state) {
          if (!onlyRecordFailures) {
              // check if containing folder exists - if it doesn't then just record failures for all supported extensions without disk probing
              var directory = ts.getDirectoryPath(candidate);
              if (directory) {
                  onlyRecordFailures = !directoryProbablyExists(directory, state.host);
              }
          }
          return ts.forEach(extensions, function (ext) {
              return !(state.skipTsx && ts.isJsxOrTsxExtension(ext)) && tryFile(candidate + ext, failedLookupLocation, onlyRecordFailures, state);
          });
      }
docs: Try to return an existing file that adds one of the `extensions` to `candidate`.