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: ph20-blackarch-core.rb
    path of file: ./repos/pentest-env/instances
    
    the code of the file until where you have to start completion: def instance(vconfig, custom)
  vconfig.vm.define custom['name'], primary: false do |blackarch|
    blackarch.vm.box = 'ph20/blackarch-core-x86_64'

    
def instance(vconfig, custom)
  vconfig.vm.define custom['name'], primary: false do |blackarch|
    blackarch.vm.box = 'ph20/blackarch-core-x86_64'
    blackarch.vm.box_check_update = false

    blackarch.vm.synced_folder '.', '/vagrant', disabled: true

    blackarch.ssh.forward_agent = true
    blackarch.ssh.forward_x11 = true

    blackarch.vm.provider 'virtualbox' do |v|
      v.gui = false
      v.customize ['modifyvm', :id, '--name', "pentest-env-#{custom['name']}"]
      v.customize ['modifyvm', :id, '--memory', 1024]
      v.customize ['modifyvm', :id, '--vrde', 'off']
    end
  end
end