code: public void addFile(String filename,int linesAdded, int linesDeleted){
  		CommitFile commitFile = new CommitFile(filename, linesAdded, linesDeleted);
  		if (files == null){
  			files = new ArrayList<CommitFile>();
  		}
  		this.files.add(commitFile);
  	}
docs: This adds a file to the list of files affected by a particular commit.
  @param filename The filename affected by the commit.
  @param linesAdded	Number of lines added in the above file in that particular commit.
  @param linesDeleted	Number of lines deleted in the above file in that particular commit.