function _fnExternApiFunc (fn)
	{
		return function() {
			var args = [_fnSettingsFromNode( this[DataTable.ext.iApiIndex] )].concat(
				Array.prototype.slice.call(arguments)
			);
			return DataTable.ext.internal[fn].apply( this, args );
		};
	}
Create a wrapper function for exporting an internal functions to an external API.
 @param {string} fn API function name
 @returns {function} wrapped function
 @memberof DataTable#internal