abstract public void Ds\Collection::clear( void )

<?php
   collection = new \Ds\Vector([1, 2, 3, 4, 5, 6]);   print_r(collection);  

   collection->clear();   print_r(collection); 
?>

<?php 
   collection = new \Ds\Vector([10, 15, 20, 25, 30, 35]);
   var_dump(collection);

   collection->clear();
   var_dump(collection); 
?>