private String getSingleLineOfChildren(List<? extends BaseToken> children) {
        StringBuilder result = new StringBuilder();
        Iterator<? extends BaseToken> childrenIt = children.iterator();
        boolean isFirst = true;

        while (childrenIt.hasNext()) {
            Object child = childrenIt.next();

            if ( !(child instanceof ContentNode) ) {
                return null;
            } else {
                String content = child.toString();

                // if first item trims it from left
                if (isFirst) {
                	content = ltrim(content);
                }

                // if last item trims it from right
                if (!childrenIt.hasNext()) {
                	content = rtrim(content);
                }

                if ( content.indexOf("\n") >= 0 || content.indexOf("\r") >= 0 ) {
                    return null;
                }
                result.append(content);
            }

            isFirst = false;
        }

        return result.toString();
    }