protected ASTNode atom() {
	Token nextToken = consume();

	if (nextToken.getType() == TokenType.END) {
	    return null;
	}

	if (nextToken.getType() == TokenType.L_PARAN) {
	    // Process compound expression
	    ASTNode tree = orExpr();
	    consume(); // remove RPAREN
	    return tree;
	} else {
	    return processLeaveNodes(nextToken);
	}

    }