class NormalCharacterPattern implements CharacterPattern {
    @Override
    public Matching match(List<Character> seq) {<FILL_FUNCTION_BODY>}

    /**
     * From http://stackoverflow.com/questions/220547/printable-char-in-java
     * @param c character to test
     * @return True if this is a 'normal', printable character, false otherwise
     */
    private static boolean isPrintableChar(char c) {
        if (Character.isISOControl(c)) { return false; }
        Character.UnicodeBlock block = Character.UnicodeBlock.of(c);
        return block != null && block != Character.UnicodeBlock.SPECIALS;
    }
}

        if (seq.size() != 1) {
            return null; // nope
        }
        char ch = seq.get(0);
        if (isPrintableChar(ch)) {
            KeyStroke ks = new KeyStroke(ch, false, false);
            return new Matching( ks );
        } else {
            return null; // nope
        }
    
<no_super_class>