public function where($key, $value)
    {
        $filter = $this->createFilter($key, $value);
        return new static(array_filter($this->source, $filter));
    }
public function where($key, $value)
    {
        $filter = $this->createFilter($key, $value);
        return new static(array_filter($this->source, $filter));
    }
public function where ( $ key , $ value ) { $ filter = $ this -> createFilter ( $ key , $ value ) ; return new static ( array_filter ( $ this -> source , $ filter ) ) ; }
Filter the attachments by role, contentType, type.

@param string $key
@param string $value

@return self
Filter the attachments by role contentType type .