# File lib/base_object.rb, line 276
      def run_command(instance_url, args)
        credentials = args[1]
        params = {
          :cmd => args[0],
          :private_key => credentials[:pem] ? File.read(credentials[:pem]) : nil,
        }
        params.merge!({
          :username => credentials[:username],
          :password => credentials[:password]
        }) if credentials[:username] and credentials[:password]
        @client.request(:post, instance_url, {}, params) do |response|
          output = Nokogiri::XML(response)
          (output/'/instance/output').first.text
        end
      end