class B is obtain the same characteristics from class A
phpstorm said unused class A, class B, attribute1, attribute2, operation1, operation2

class A {
    public $attribute1;
    function operation1(){
        echo "operation1";
        echo "<br/>";
    }
}
class B extends A {
    public $attribute2;
    function operation2(){
        echo "operation2";
        echo "<br/>";
    }
}
$b = new B();
$b->operation1();
$b->attribute1 = 10;
$b->operation2();
$b->attribute2 = 10;
echo $b->attribute1;
echo "<br/>";
echo $b->attribute2;
echo "<br/>";

$a = new A();
$a->operation1();
$a->attribute1 = 10;
/*It is important to note that inheritance works in only one direction. 
The subclass or child inherits features from its parent of superclass,
 but the parent does not take on features of the child. 
 This means tha the last two lines in this code make no sense*/
$a->operation2();
$a->attribute2 = 10
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