code: function (fileName) {
              if (!file.exists(fileName)) {
                  try {
                      //Try to find the path of the file thanks to node's require resolving.
                      fileName = nodeRequire.resolve(fileName);
                  } catch(e) {}
              }
              return frontSlash(path.normalize(frontSlash(fs.realpathSync(fileName))));
          }
docs: Gets the absolute file path as a string, normalized
  to using front slashes for path separators.
  @param {String} fileName