How to use the peru.rule.Rule function in peru

def test_parse_module_default_rule(self):
        input = dedent("""\
            git module bar:
                export: bar
            """)
        scope, imports = parse_string(input)
        self.assertIn("bar", scope.modules)
        module = scope.modules["bar"]
        self.assertIsInstance(module, Module)
        self.assertIsInstance(module.default_rule, Rule)
        self.assertEqual(module.default_rule.export, "bar")

def test_parse_rule(self):
        input = dedent("""\
            rule foo:
                export: out/
            """)
        scope, imports = parse_string(input)
        self.assertIn("foo", scope.rules)
        rule = scope.rules["foo"]
        self.assertIsInstance(rule, Rule)
        self.assertEqual(rule.name, "foo")
        self.assertEqual(rule.export, "out/")

def extract_rules(blob):
    rules = {}
    for field in list(blob.keys()):
        parts = field.split()
        if len(parts) == 2 and parts[0] == "rule":
            inner_blob = blob.pop(field)  # remove the field from blob
            name = parts[1]
            rules[name] = rule.Rule(name, inner_blob)
    return rules

if bad_keys:
            raise RuntimeError("unknown module fields: {}".format(
                ", ".join(bad_keys)))
        overlapping_names = rules.keys() & modules.keys()
        if overlapping_names:
            raise RuntimeError("rules and modules with the same name: " +
                               ", ".join(overlapping_names))
        self.fields = blob
        self.rules = rules
        self.modules = modules
        self.name = name
        self.remote = remote
        if "rule" in self.fields:
            self.default_rule = rule.Rule("", self.fields["rule"])
        else:
            self.default_rule = rule.Rule("", {})

field_names = {"imports", "rule"}
        bad_keys = blob.keys() - field_names
        if bad_keys:
            raise RuntimeError("unknown module fields: {}".format(
                ", ".join(bad_keys)))
        overlapping_names = rules.keys() & modules.keys()
        if overlapping_names:
            raise RuntimeError("rules and modules with the same name: " +
                               ", ".join(overlapping_names))
        self.fields = blob
        self.rules = rules
        self.modules = modules
        self.name = name
        self.remote = remote
        if "rule" in self.fields:
            self.default_rule = rule.Rule("", self.fields["rule"])
        else:
            self.default_rule = rule.Rule("", {})

raise ParserError(
            textwrap.dedent('''\
            The "build" field is no longer supported. If you need to
            untar/unzip a curl module, use the "unpack" field.'''))
    if 'files' in blob:
        raise ParserError(
            'The "files" field is no longer supported. Use "pick" instead.')
    copy = _extract_multimap_field(blob, 'copy')
    move = _extract_multimap_field(blob, 'move')
    executable = _extract_optional_list_field(blob, 'executable')
    drop = _extract_optional_list_field(blob, 'drop')
    pick = _extract_optional_list_field(blob, 'pick')
    export = typesafe_pop(blob, 'export', None)
    if not any((copy, move, executable, drop, pick, export)):
        return None
    rule = Rule(name, copy, move, executable, drop, pick, export)
    return rule