    # File lib/chef/provider/deploy.rb, line 177
          def callback(what, callback_code=nil)
            @collection = Chef::ResourceCollection.new
            case callback_code
            when Proc
              Chef::Log.info "#{@new_resource} running callback #{what}"
              recipe_eval(&callback_code)
            when String
              run_callback_from_file("#{release_path}/#{callback_code}")
            when nil
              run_callback_from_file("#{release_path}/deploy/#{what}.rb")
            end
          end