Undefined array key "upload_link"

[chiporgar7]

Hello I have copied as it is in the documentation of how to upload a video like this

$file_name = "{path_to_a_video_on_the_file_system}";
$uri = $client->upload($file_name, array(
  "name" => "Untitled",
  "description" => "The description goes here."
));

echo "Your video URI is: " . $uri;'

but I get an error like this

ok, actually my code is like this.

 $uri = Vimeo::connection()->upload($this->video->getPathName(), array(
            "body" => $this->_title_,
            "description"  => $this->_description_,
          ));

ok, I know it says the key is missing from the array. I have added it but it keeps giving me the same error

 $uri = Vimeo::connection()->upload($this->video->getPathName(), array(
            "body" => $this->_title_,
            "description"  => $this->_description_, 
            "upload_link" =>  (but what do I put here?)

          ));

in the upload_link key I have put whatever. but it doesn't work either