WordPress is a free software, and those freedoms are partially about providing the ability to learn from the software. Reading the source will provide you with an understanding of your software, and a learning experience that no documentation can provide.
Slides and links from my WPSessions talk on using Composer for WordPress plugin development.
Not sure how it took me so long to figure this one out, but you can use a WP_Post object to get a post_meta key, by using the key as a property of the object. Very cool use of the __get() magic method
array_column() is a great way to avoid using foreach loops to find a an index of a dimensional array that contains a specific value, in a specific index.