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: isolated_environment.rb
    path of file: ./repos/vagrant/test/unit/support
    
    the code of the file until where you have to start completion: # Copyright (c) HashiCorp, Inc.
# SPDX-License-Identifier: BUSL-1.1

require
    
    def box(name, vagrantfile_contents="")
      # Create the box directory
      box_dir = boxes_dir.join(name)
      box_dir.mkpath

      # Create the "box.ovf" file because that is how Vagrant heuristically
      # determines a box is a V1 box.
      box_dir.join("box.ovf").open("w") { |f| f.write("") }

      # Populate the vagrantfile
      vagrantfile(vagrantfile_contents, box_dir)

      # Return the directory
      box_dir
    end