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: common.rb
    path of file: ./repos/landrush/lib/landrush/action
    
    the code of the file until where you have to start completion: module Landrush
  module Action
    # A module containing shared functionality for Vagrant middleware classes
    module Common
      SUPPORTED_PROVIDERS = {
        'VagrantPlugins::ProviderVirtualB
    
      def provider
        provider_name = SUPPORTED_PROVIDERS.fetch(machine.provider.class.name) do |key|
          raise "The landrush plugin does not support the #{key} provider yet!"
        end

        if provider_name == :parallels && Gem::Version.new(VagrantPlugins::Parallels::VERSION) < Gem::Version.new('1.0.3')
          raise "The landrush plugin supports the Parallels provider v1.0.3 and later. Please, update your 'vagrant-parallels' plugin."
        end

        provider_name
      end