Description of problem:

The doc/examples/list_obsoletes_plugin.py example does not work out of box.

Version-Release number of selected component (if applicable):

Testing on Fedora rawhide with dnf-4.0.10-1.fc30.noarch.

How reproducible:

Deterministic.

Steps to Reproduce:
1. Copy doc/examples/list_obsoletes_plugin.py from dnf master to /usr/lib/python3.7/site-packages/dnf-plugins/foo.py
2. Try to test with dnf foo

Actual results:

# dnf foo
Traceback (most recent call last):
  File "/usr/bin/dnf", line 58, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python3.7/site-packages/dnf/cli/main.py", line 179, in user_main
    errcode = main(args)
  File "/usr/lib/python3.7/site-packages/dnf/cli/main.py", line 64, in main
    return _main(base, args, cli_class, option_parser_class)
  File "/usr/lib/python3.7/site-packages/dnf/cli/main.py", line 95, in _main
    cli.configure(list(map(ucd, args)), option_parser())
  File "/usr/lib/python3.7/site-packages/dnf/cli/cli.py", line 966, in configure
    self.command.configure()
TypeError: configure() missing 1 required positional argument: 'args'

Expected results:

No error, presumably obsoleted packages should be listed.

Additional info: