Set#proper_superset?

# File tmp/rubies/ruby-3.1.3/lib/set.rb, line 422
def proper_superset?(set)
  case
  when set.instance_of?(self.class) && @hash.respond_to?(:>)
    @hash > set.instance_variable_get(:@hash)
  when set.is_a?(Set)
    size > set.size && set.all? { |o| include?(o) }
  else
    raise ArgumentError, "value must be a set"
  end
end