code: public FileFormat determineFileFormat(File bibfile)
  			throws FileNotFoundException, IOException {
  		if (!bibfile.exists()) {
  			throw new FileNotFoundException("Bibliography file `" + 
  					bibfile.getName() + "' does not exist");
  		}
  		try (BufferedInputStream bis = new BufferedInputStream(
  				new FileInputStream(bibfile))) {
  			return determineFileFormat(bis, bibfile.getName());
  		}
  	}
docs: Reads the first 100 KB of the given bibliography file and tries
  to determine the file format
  @param bibfile the input file
  @return the file format (or {@link FileFormat#UNKNOWN} if the format
  could not be determined)
  @throws FileNotFoundException if the input file was not found
  @throws IOException if the input file could not be read