# File lib/hashie/dash.rb, line 61
    def self.inherited(klass)
      super
      (@subclasses ||= Set.new) << klass
      klass.instance_variable_set('@properties', properties.dup)
      klass.instance_variable_set('@defaults', defaults.dup)
      klass.instance_variable_set('@required_properties', required_properties.dup)
    end