code: public static Formula readPropositionalFormula(final String fileName, final FormulaFactory f) throws IOException, ParserException {
      return read(new File(fileName), new PropositionalParser(f));
    }
docs: Reads a given file and returns the contained propositional formula.
  @param fileName the file name
  @param f        the formula factory
  @return the parsed formula
  @throws IOException     if there was a problem reading the file
  @throws ParserException if there was a problem parsing the formula