public function insert( $position, $string )
	{
		if( $position<= $this->count() && $position >=0 )
		{
			if( $position < $this->pointer )
				$this->pointer = $this->pointer + strlen( $string );
			$left	= substr( $this->toString(), 0, $position );
			$right	= substr( $this->toString(), $position );
			$this->buffer = $left.$string.$right;
		}
		return $this->toString();
	}