[bugfix] Updating examples

[GetOutOfMyBakery]

What

A few of the examples could do with a few improvements:

• clear.rb wasn't setting clear: true, so not exhibiting the feature
• updated the glyphs for custom_style.rb
• multi/threaded.rb was broken, due to Ruby 3.0 changes. I've fixed it and added random success/errors to better demonstrate the example.