code: public Expression parse(ExpressionIterator expressionIterator, @NonNull ParserToken token) throws ParseException {
        PrefixHandler handler = prefixHandlers.containsKey(token.type)
                                ? prefixHandlers.get(token.type)
                                : prefixSkipHandler;
        if (handler == null) {
           throw new ParseException("No PrefixHandler registered for token type " + token.type);
        }
        return handler.parse(expressionIterator, token);
     }
docs: Parses a prefix expression
  
  @param expressionIterator The parser to use
  @param token              The token causing the prefix parse
  @return A parsed expression
  @throws ParseException Something went wrong parsing.