Question about php namespace

What is the meaning of this writing method that is not found in the official manual?

<code class="php">namespace {
    $test = 'a';
}

namespace {
    if($test == 'a'){
        //do something
    }
}</code>

Reply content:

What is the meaning of this writing method that is not found in the official manual?

<code class="php">namespace {
    $test = 'a';
}

namespace {
    if($test == 'a'){
        //do something
    }
}</code>

You can take a look. When optimizing before, I used this method to merge multiple files of the framework into one.
The manual address is: http://php.net/manual/zh/language.namespaces.definitionmultiple.php

I tried it locally and found a problem

<code>namespace a
{
    class abc
    {
        private $test = 'a';
        public function ceshi()
        {
            echo $this->test;
        }
    }
}

namespace {
    $ceshi = new a\abc();
    $ceshi->ceshi();
}
</code>

and

<code>namespace a;
class abc
{
    private $test = 'a';
    public function ceshi()
    {
        echo $this->test;
    }
}

namespace b;

class abc
{
    private $test = 'b';
    public function ceshi()
    {
        echo $this->test;
    }
}
use a;
$ceshi = new a\abc();
$ceshi->ceshi();</code>

The meaning is almost the same. The first one is global call