TalkPHP - pfp fatal error:cannot redeclare extract()

dear all
I am new in php programing and I wrote one function in which I am trying to remove an index from an array using "array_splice".but I don't know i am using in a proper way or not.so please tell me how to remove an index from an array and this fatal error..
I am including my code :
thanks

Code:

<?php

function extract($this)

{

        if($this->parent)

        {

                try

                {     

                array_splice($parent->content,$this);

            }

            catch(Exception $e)

                        {

                                }



         }

        $lastChild=$this->lastRecursiveChild();

        $nextElement =$lastChild->next;



        if($this->previous)

         {

                $this->previous->next=$nextElement;

         }

        if($nextElement)

         {

                $nextElement->previous=$this->previous;

         }

        $this->previous=null;

        $lastChild->next = Null;

        $this->parent = Null;

        if ($this->previousSibling)

        {

                $this->previousSibling->nextSibling = $this->nextSibling;

        }

         if ($this->nextSibling)

        {

                $this->nextSibling->previousSibling = $this->previousSibling;

         }

        $this->previousSibling = $this->nextSibling = Null;

        return $this;

}

?>