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: unbound.rb
    path of file: ./repos/homebrew-core/Formula/u
    
    the code of the file until where you have to start completion: class Unbound < For
    
  def post_install
    conf = etc/"unbound/unbound.conf"
    return unless conf.exist?
    return unless conf.read.include?('username: "@@HOMEBREW-UNBOUND-USER@@"')

    inreplace conf, 'username: "@@HOMEBREW-UNBOUND-USER@@"',
                    "username: \"#{ENV["USER"]}\""
  end