add separate extension

lib/extension/separate_extension.dart

@@ -0,0 +1,13 @@
+import 'package:ansu_ui/ansu_ui.dart';
+import 'package:flutter/material.dart';
+
+extension SeparateExt on List {
+  List sep([Widget separate]) {
+    return List.generate(this.length * 2 - 1, (index) {
+      if (index.isEven)
+        return this[index ~/ 2];
+      else
+        return separate ?? 10.wb;
+    });
+  }
+}