def uuid_from_command
      return unless @platform[:uuid_command]
      result = @backend.run_command(@platform[:uuid_command])
      uuid_from_string(result.stdout.chomp) if result.exit_status.zero? && !result.stdout.empty?
    end
def uuid_from_command
      return unless @platform[:uuid_command]
      result = @backend.run_command(@platform[:uuid_command])
      uuid_from_string(result.stdout.chomp) if result.exit_status.zero? && !result.stdout.empty?
    end
This takes a command from the platform detect block to run.
 We expect the command to return a unique identifier which
 we turn into a UUID.