function _fnApplyToChildren( fn, an1, an2 )
	{
		var index=0, i=0, iLen=an1.length;
		var nNode1, nNode2;
	
		while ( i < iLen ) {
			nNode1 = an1[i].firstChild;
			nNode2 = an2 ? an2[i].firstChild : null;
	
			while ( nNode1 ) {
				if ( nNode1.nodeType === 1 ) {
					if ( an2 ) {
						fn( nNode1, nNode2, index );
					}
					else {
						fn( nNode1, index );
					}
	
					index++;
				}
	
				nNode1 = nNode1.nextSibling;
				nNode2 = an2 ? nNode2.nextSibling : null;
			}
	
			i++;
		}
	}
Apply a given function to the display child nodes of an element array (typically
TD children of TR rows
 @param {function} fn Method to apply to the objects
 @param array {nodes} an1 List of elements to look through for display children
 @param array {nodes} an2 Another list (identical structure to the first) - optional
 @memberof DataTable#oApi