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: index_state.rb
    path of file: ./repos/archivesspace/indexer/app/lib
    
    the code of the file until where you have to start completion: # we store the state of uri's index in the indexer_state directory
class IndexState

  def initial
    
  def get_last_mtime(repository_id, record_type)
    path = path_for(repository_id, record_type)

    begin
      File.open("#{path}.dat", "r") do |fh|
        fh.readline.to_i
      end
    rescue Errno::ENOENT
      # If we've never run against this repository_id/type before, just index
      # everything.
      0
    end