# File lib/json/add/core.rb, line 25
  def self.json_create(object)
    civil(*object.values_at('y', 'm', 'd', 'sg'))
  end

# File lib/json/add/core.rb, line 29
  def to_json(*args)
    {
      'json_class' => self.class.name,
      'y' => year,
      'm' => month,
      'd' => day,
      'sg' => sg,
    }.to_json(*args)
  end