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: event.rb
    path of file: ./repos/hitobito/app/models/person/add_request
    
    the code of the file until where you have to start completion: # encoding: utf-8

#  Copyright
    
  def to_s(_format = :default)
    if body
      group = body.groups.first
      event_label = body_label
      group_label = "#{group.model_name.human} #{group}"
      self.class.human_attribute_name(:label, body: event_label, group: group_label)
    else
      # event was deleted in the mean time
      self.class.human_attribute_name(:deleted_event)
    end