def METHOD_NAME(self, msg):
    """
    Asserts the correct packages are associated with the flexible tag.
    Namely, 'annakarenina' and 'warandpeace'.
    """
    data = self.loads(msg)
    pkgs = set(data)
    expected_pkgs = set(
        [
            self.package_ref_from_name("annakarenina"),
            self.package_ref_from_name("warandpeace"),
        ]
    )
    differences = expected_pkgs ^ pkgs
    assert not differences, "%r != %r" % (pkgs, expected_pkgs)