class ActionView::Helpers::Tags::GroupedCollectionSelect

def initialize(object_name, method_name, template_object, collection, group_method, group_label_method, option_key_method, option_value_method, options, html_options)
  @collection          = collection
  @group_method        = group_method
  @group_label_method  = group_label_method
  @option_key_method   = option_key_method
  @option_value_method = option_value_method
  @html_options        = html_options
  super(object_name, method_name, template_object, options)
end

def render
  option_tags_options = {
    selected: @options.fetch(:selected) { value },
    disabled: @options[:disabled]
  }
  select_content_tag(
    option_groups_from_collection_for_select(@collection, @group_method, @group_label_method, @option_key_method, @option_value_method, option_tags_options), @options, @html_options
  )
end