Adding A Custom Command To Lona Shell

# commands/hello_world.py

from rlpython.utils.argument_parser import ReplArgumentParser


class HelloWorldCommand:
    """
    prints "Hello World"
    """

    NAME = 'hello_world'

    def __init__(self, repl):
        self.repl = repl

    def complete(self, text, state, line_buffer):
        # tab completion (optional)

        raw_candidates = ['Hello', 'World']
        candidates = []

        for candidate in raw_candidates:
            if candidate.startswith(text)
                candidates.append(candidate)

        candidates.append(None)

        return candidates[state]

    def run(self, argv):
        # getting a reference to the currently running lona server
        server = self.repl.locals['server']

        # parse command line
        argument_parser = ReplArgumentParser(
            repl=self.repl,
            prog='hello_world',
        )

        argument_parser.add_argument('--silent')

        arguments = argument_parser.parse_args(argv[1:])

        # print hello world
        if not arguments.silent:
            self.repl.write('Hello World\n')

# settings.py

COMMANDS = [
    'commands/hello_world.py::HelloWorldCommand',
]