Can't run test example

[tarasinf]

Thy to run:

  docker run --rm \
    -e REGISTRY_CLI_HOSTNAME=registry.gitlab.com \
    -e REGISTRY_CLI_USERNAME=a***z \
    -e REGISTRY_CLI_PASSWORD=a***z \
    jack12816/plankton tags

Got response:

Commands:
  plankton cleanup REPO    # Cleanup a given repository
  plankton help [COMMAND]  # Describe available commands or one specific command
  plankton rmtag REPO TAG  # Delete a given tag
  plankton tag REPO TAG    # All the details of of a given tag
  plankton tags REPO       # List all tags of a given repository

Options:
  -h, [--hostname=HOSTNAME]        # The Docker Registry to work with
  -u, [--username=USERNAME]        # The username for authentication
  -p, [--password=PASSWORD]        # The password for authentication
      [--confirm], [--no-confirm]  # User interaction is required
                                   # Default: true
  -v, [--verbose], [--no-verbose]  # Be verbose while processing


Environment:
  REGISTRY_CLI_HOSTNAME  # Specify the Docker Registry hostame
                         # --username takes precedence over the env var
  REGISTRY_CLI_USERNAME  # The username for authentication
                         # --hostname takes precedence over the env var
  REGISTRY_CLI_PASSWORD  # The password for authentication
                         # --password takes precedence over the env var

Could you help to identify the reason?