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: postgresql.rb
    path of file: ./repos/backup/lib/backup/database
    
    the code of the file until where you have to start completion: module Backup
  module Database
    class PostgreSQL < Base
      class Error
    
      def connectivity_options
        return "--host='#{socket}'" if socket

        opts = []
        opts << "--host='#{host}'" if host
        opts << "--port='#{port}'" if port
        opts.join(" ")
      end