a.rb

 if aAccepted.any? do |di|
      di.include? event.start.dateTime.to_date || (di.include? event.end.dateTime.to_date)
    end
      drop = client.execute!(:api_method => calendar_api.events.get,
                             :parameters => {'calendarId' => 'primary', 'eventId' => event.id})

      drop_event = drop.data
      drop_event.attendees[0].responseStatus = 'declined'
      drop = client.execute!(:api_method => calendar_api.events.update,
                             :parameters => {'calendarId' => 'primary', 'eventId' => event.id},
                             :body_object => drop_event,
                             :headers => {'Content-Type' => 'application/json'})

      m = Gmail::Message.new(to: event.organizer.email, subjet: "Status: OK", html: "Booking OK")
      m.deliver
    end