the original demo code in README is:

The Date#format Method
class Date
  def format( spec ) self.strftime( spec.to_strftime ); end
end
The new Date#format method formats the date like the passed in example:

date = Date.today   ## test run on 2020-02-09

p date.format( 'January 02, 2006' )         #=> "February 09, 2020"

but the 'format' method is a built in stdlib privat

The main display function checks if fading then - else - check filter. The quick filter button doesn't have this check. This could lead to some very funny results.