private function makeChannels()
    {
        $out = '';

        //Start channel tag
        switch ($this->version) {
            case Feed::RSS2:
                $out .= '<channel>' . PHP_EOL;
                break;
            case Feed::RSS1:
                $out .= (isset($this->data['ChannelAbout']))? "<channel rdf:about=\"{$this->data['ChannelAbout']}\">" : "<channel rdf:about=\"{$this->channels['link']['content']}\">";
                break;
        }

        //Print Items of channel
        foreach ($this->channels as $key => $value) {
            // In ATOM feeds, strip all ATOM namespace prefixes from the tag name. They are not needed here,
            // because the ATOM namespace name is set as default namespace.
            if ($this->version == Feed::ATOM && strncmp($key, 'atom', 4) == 0) {
                $key = substr($key, 5);
            }

            // The channel element can occur multiple times, when the key 'content' is not in the array.
            if (!array_key_exists('content', $value)) {
                // If this is the case, iterate through the array with the multiple elements.
                foreach ($value as $singleElement) {
                    $out .= $this->makeNode($key, $singleElement['content'], $singleElement['attributes']);
                }
            } else {
                $out .= $this->makeNode($key, $value['content'], $value['attributes']);
            }
        }

        if ($this->version == Feed::RSS1) {
            //RSS 1.0 have special tag <rdf:Seq> with channel
            $out .= "<items>" . PHP_EOL . "<rdf:Seq>" . PHP_EOL;
            foreach ($this->items as $item) {
                $thisItems = $item->getElements();
                $out .= "<rdf:li resource=\"{$thisItems['link']['content']}\"/>" . PHP_EOL;
            }
            $out .= "</rdf:Seq>" . PHP_EOL . "</items>" . PHP_EOL . "</channel>" . PHP_EOL;

            // An image has its own element after the channel elements.
            if (array_key_exists('image', $this->data))
                $out .= $this->makeNode('image', $this->data['Image'], array('rdf:about' => $this->data['Image']['url']));
        } else if ($this->version == Feed::ATOM) {
            // ATOM feeds have a unique feed ID. Use the title channel element as key.
            $out .= $this->makeNode('id', Feed::uuid($this->channels['title']['content'], 'urn:uuid:'));
        }

        return $out;
    }