old_contents: import sh
  from sh import docker
  
  from utils import get_ip, delete_container
  
  
  class DockerHost(object):
      """
      A host container which will hold workload containers to be networked by calico.
      """
      def __init__(self, name):
          """
          Create a container using an image made for docker-in-docker. Load saved images into it.
          """
          self.name = name
  
          pwd = sh.pwd().stdout.rstrip()
          docker.run("--privileged", "-v", pwd+":/code", "--name", self.name, "-tid", "jpetazzo/dind")
  
          self.ip = docker.inspect("--format", "{{ .NetworkSettings.IPAddress }}",
                                   self.name).stdout.rstrip()
          self.execute("while ! docker ps; do sleep 1; done && "
                       "docker load --input /code/calico_containers/calico-node.tar && "
                       "docker load --input /code/calico_containers/busybox.tar && "
                       "docker load --input /code/calico_containers/nsenter.tar")
  
      def _listen(self, stdin, **kwargs):
          """
          Feed a raw command to a container via stdin.
          """
          return docker("exec", "--interactive", self.name,
                        "bash", s=True, _in=stdin, **kwargs)
  
      def execute(self, command, use_powerstrip=False, **kwargs):
          """
          Pass a command into a host container. Appends some environment
          variables and then calls out to DockerHost._listen. This uses stdin via
          'bash -s' which is more forgiving of bash syntax than 'bash -c'.
  
          :param use_powerstrip: When true this sets the DOCKER_HOST env var. This
          routes through Powerstrip, so that Calico can be informed of the changes.
          """
          etcd_auth = "export ETCD_AUTHORITY=%s:2379;" % get_ip()
          stdin = ' '.join([etcd_auth, command])
  
          if use_powerstrip:
              docker_host = "export DOCKER_HOST=localhost:2377;"
              stdin = ' '.join([docker_host, stdin])
          return self._listen(stdin, **kwargs)
  
      def calicoctl(self, command, **kwargs):
          calicoctl = "/code/dist/calicoctl %s"
          self.execute(calicoctl % command, **kwargs)
  
      def delete(self):
          """
          Have a container delete itself.
          """
          delete_container(self.name)
  
new_contents: import sh
  from sh import docker
  
  from utils import get_ip, delete_container
  
  
  class DockerHost(object):
      """
      A host container which will hold workload containers to be networked by calico.
      """
      def __init__(self, name):
          """
          Create a container using an image made for docker-in-docker. Load saved images into it.
          """
          self.name = name
  
          pwd = sh.pwd().stdout.rstrip()
          docker.run("--privileged", "-v", pwd+":/code", "--name", self.name, "-tid", "jpetazzo/dind")
  
          self.ip = docker.inspect("--format", "{{ .NetworkSettings.IPAddress }}",
                                   self.name).stdout.rstrip()
          self.execute("while ! docker ps; do sleep 1; done && "
                       "docker load --input /code/calico_containers/calico-node.tar && "
                       "docker load --input /code/calico_containers/busybox.tar && "
                       "docker load --input /code/calico_containers/nsenter.tar")
  
      def _listen(self, stdin, **kwargs):
          """
          Feed a raw command to a container via stdin.
          """
          return docker("exec", "--interactive", self.name,
                        "bash", s=True, _in=stdin, **kwargs)
  
      def execute(self, command, use_powerstrip=False, **kwargs):
          """
          Pass a command into a host container. Appends some environment
          variables and then calls out to DockerHost._listen. This uses stdin via
          'bash -s' which is more forgiving of bash syntax than 'bash -c'.
  
          :param use_powerstrip: When true this sets the DOCKER_HOST env var. This
          routes through Powerstrip, so that Calico can be informed of the changes.
          """
          etcd_auth = "export ETCD_AUTHORITY=%s:2379;" % get_ip()
          stdin = ' '.join([etcd_auth, command])
  
          if use_powerstrip:
              docker_host = "export DOCKER_HOST=localhost:2377;"
              stdin = ' '.join([docker_host, stdin])
          return self._listen(stdin, **kwargs)
  
      def calicoctl(self, command, **kwargs):
          calicoctl = "/code/dist/calicoctl %s"
          return self.execute(calicoctl % command, **kwargs)
  
      def delete(self):
          """
          Have a container delete itself.
          """
          delete_container(self.name)
  
subject: Add return statement.