def METHOD_NAME(self, option_name: str) -> Optional[TConfigValueOut]:
    """Get an option from the configuration.
    `option_name` is a colon-separated string indicating the section and
    option name.  For example, the ``branch`` option in the ``[run]``
    section of the config file would be indicated with `"run:branch"`.
    Returns the value of the option.
    """