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: available.rb
    path of file: ./repos/ReadyResponder/app/services/msg
    
    the code of the file until where you have to start completion: class Msg::Ava
    
  def respond
    case event_codename
    when "custom"
      # available custom 1/15/2017 0800 01/15/2021 Work
      unless start_time.is_a? Time and end_time.is_a? Time
        return "Error! Sample => available custom 2016-11-23 00:01 2017-12-31 17:00 Leave of absense <="
      end