Expandable JSON code samples

How to tell a user that code samples are available, but they are hidden out of the view? We've had this issue where some of the code samples were automatically collapsed by the application that generated them, and the user would only see one line of code. It was extremely not intuitive that it was possible to see inside those samples.

Eventually we figured out a way to overwrite the collapsing and to show the top-level code in its depth, thus having enough code to read, yet hiding most of its complexity.

This was a WIP to try and give user an interactive way to know that expansion was possible. The idea was to actually show that "hand" graphic with an overlay, thus explicitly pointing out the feature.