How to make a custom column in Flex 4.5 datagrid

<s:GridColumn >
<s:itemRenderer >
<fx:Component >
<s:GridItemRenderer >
<fx:Script >
<![CDATA[

override public function set data( value:Object ) : void {

if(!value)

return;

trace(value);

super.data = value;

txtAreaColumn.text = value.Definition;

}

]] >
</fx:Script >
<s:TextArea heightInLines="1" id="txtAreaColumn" / >
</s:GridItemRenderer >
</fx:Component >
</s:itemRenderer >
</s:GridColumn >