Trouble implementing python on WordPress

I followed all the directions in this post and I still cannot get a result to display. I know PHP is doing something, because there is no text displayed whatsoever. The result has a header and no body content. When the plugin is disabled, it displays the shortcode as plain text.

<?php # -*- coding: utf-8 -*-
/* Plugin Name: Python embedded */

add_shortcode( 'python', 'embed_python' );

function embed_python( $attributes )
{
    $data = shortcode_atts(
        array(
            'file' => 'hello.py'
        ),
        $attributes
    );
    $handle = popen( __DIR__ . '/' . $data['file'], 'r');
    $read   = fread($handle, 2096);
    pclose($handle);

    return $read;
}

I uploaded hello.py and Python.php to the plugins folder and made sure the plugin was properly activated.

In my post editor I have: [python file="hello.py"].