You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: acts_as_op_engine.rb
    path of file: ./repos/openproject/lib/open_project/plugins
    
    the code of the file until where you have to start completion: #-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2024 the OpenProject GmbH
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License version 3.
#
# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
# Copyright (C) 2006-2013 Jean-Philippe Lang
# Copyright (C) 2010-2013 the ChiliProject Team
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# See COPYRIGHT and LICENSE files for more details.
#++

require 'open_project/ui/extensible_tabs'
require_relative '../../../config/constants/api_patch_registry'
require_relative '../../../config/constants/open_project/activity'
require_relative '
    
      def add_api_endpoint(base_endpoint, path = nil, &)
        # we are expecting the base_endpoint as string for two reasons:
        # 1. it does not seem possible to pass it as constant (auto loader not ready yet)
        # 2. we can't constantize it here, because that would evaluate
        #    the API before it can be patched
        ::Constants::APIPatchRegistry.add_patch(base_endpoint, path, &)
      end

      def extend_api_response(*args, &)
        config.to_prepare do
          representer_namespace = args.map { |arg| arg.to_s.camelize }.join('::')
          representer_class     = "::API::#{representer_namespace}Representer".constantize
          representer_class.instance_eval(&)
        end
      end

      def add_api_attribute(on:,
                            ar_name:,
                            writable_for: %i[create update],
                            writable: true,
                            &block)
        config.to_prepare do
          model_name = on.to_s.camelize
          namespace = model_name.pluralize
          Array(writable_for).each do |action|
            # attribute is generally writable
            # overrides might be defined in the more specific contract implementations
            contract_class = "::#{namespace}::#{action.to_s.camelize}Contract".constantize
            contract_class.attribute ar_name, { writable: }, &block
          end
        end
      end

      # Register a block to return results when an api representer's cache key is asked for.
      #
      # This is important for cache invalidation e.g. when another schema needs
      # to be returned depending on whether a module is active or not.
      #
      # path:          The fully namespaced representer name, excluding 'API' at the
      #                beginning and 'Representer' at the end.
      # keys:          The block to be executed when the cache key is queried for. The block's
      #                results will be appended to the original cache key if a cache key is already
      #                defined. If no cache key was defined before, the block's result makes up
      #                the whole cache key.
      def add_api_representer_cache_key(*path,
                                        &)
        mod = Module.new
        mod.send :define_method, :json_cache_key do
          if defined?(super)
            existing = super()

            existing + instance_eval(&)
          else
            instance_eval(&)
          end
        end

        config.to_prepare do
          representer_namespace = path.map { |arg| arg.to_s.camelize }.join('::')
          representer_class     = "::API::#{representer_namespace}Representer".constantize
          representer_class.prepend mod
        end
      end