Create a border in a world with a command

I want to create a border in a world with a command

example

/ Example border (blocks)


please help

 

You mean a border that no one can pass? Like the world border one in the Java version of Minecraft?

 

exact

It's for a plugin


Is something I saw in the plugin WorldProtect

And I want to do it but for a minigame help me please

 

The code is not understood very well and also depends on many more things and putting everything together is difficult

 

Then learn api of pocketmine