Find settings from all sources.

        :keyword strict: fail if unknown args are passed in.
        :returns: dict of parsed option name and values
        :raises: SystemExit if invalid arguments supplied along with stdout
            message (same as argparser).

def parse(self, argv=None, keyring_namespace=None, strict=False):
        """Find settings from all sources.

        :keyword strict: fail if unknown args are passed in.
        :returns: dict of parsed option name and values
        :raises: SystemExit if invalid arguments supplied along with stdout
            message (same as argparser).
        """
        if argv is None:
            argv = self._argv or sys.argv
        results = self.load_options(argv=argv,
                                    keyring_namespace=keyring_namespace)
        # Run validation
        results = self.validate_config(results, argv=argv, strict=strict)
        self._values = results
        return self