code: public File getFileFromModifiedFilesToCommit(int index) {
      CheckUtilities.checkIntIndexInListRange(modifiedFilesToCommit, index);
      return modifiedFilesToCommit.get(index);
    }
docs: Get the name of the file that is modified and added to the repository by &lt;git-add&gt;
  command and will be committed to repository next time &lt;git-commit&gt; is executed. This file
  is at the given index in the list of the files.
  
  @param index
  Index in the list of files must be positive and less than the number of new files to
  commit
  @return the name of the file.