private boolean checkWhitespace() {
		char read = (char) readAhead;
		if(read==' ' || read=='\t') {
			do {
				readNext();
				read = (char) readAhead;
			} while(read!=' ' && read!='\t');
			return true;
		} else {
			error("expected whitespace found: '" + read + "'");
			return false;
		}
	}