PHP에서 Ds\Queue pop() 함수를 사용하는 방법은 무엇입니까?

mixed public DsPriorityQueue::pop ( void )

<?php 
  
// Declare new Queue 
$q = new DsQueue(); 
  
// Add elements to the Queue
$q ->push( "One" );
$q ->push( "Two" );
$q ->push( "Three" );
  
echo "Initial Queue is: n" ;
print_r( $q );
  
// Pop an element
echo "nPopped element is: " ;
print_r( $q ->pop());
  
echo "nnFinal Queue is: n" ;
print_r( $q );
  
?>

Initial Queue is: 
DsQueue Object
(
    [0] => One
    [1] => Two
    [2] => Three
)

Popped element is: One

Final Queue is: 
DsQueue Object
(
    [0] => Two
    [1] => Three
)

<?php 
  
// Declare new Queue
$q = new DsQueue(); 
  
// Add elements to the Queue
$q ->push( "Geeks" );
$q ->push( "for" );
$q ->push( "Geeks" );
  
echo "Initial Queue is: n" ;
print_r( $q );
  
// Pop an element
echo "nPopped element is: " ;
print_r( $q ->pop());
  
echo "nnFinal Queue is: n" ;
print_r( $q );
  
?>

Initial Queue is: 
DsQueue Object
(
    [0] => Geeks
    [1] => for
    [2] => Geeks
)

Popped element is: Geeks

Final Queue is: 
DsQueue Object
(
    [0] => for
    [1] => Geeks
)