In the demos, at the bottom of some of the files, I see code that says.

 piklist('shared/meta-field-welcome', array(
    'location' => __FILE__
  ));

What is the purpose of this code?
In the demo, I found this file here:
plugins\piklist\add-ons\piklist-demos\parts\media\fields.php

I also see a similiar code: plugins\piklist\add-ons\piklist-demos\parts\meta-boxes\field-upload.php

  piklist('shared/code-locater', array(
    'location' => __FILE__
    ,'type' => 'Meta Box'
  ));