public function add($element)
    {
        if (!$this->contains($element)) {
            $hash = $this->hash($element);
            $this->hashTable[$hash][] = $element;
            return true;
        }
        return false;
    }
public function add($element)
    {
        if (!$this->contains($element)) {
            $hash = $this->hash($element);
            $this->hashTable[$hash][] = $element;
            return true;
        }
        return false;
    }
public function add ( $ element ) { if ( ! $ this -> contains ( $ element ) ) { $ hash = $ this -> hash ( $ element ) ; $ this -> hashTable [ $ hash ] [ ] = $ element ; return true ; } return false ; }
Add the element to this set.

@param mixed $element
@return boolean
Add the element to this set .