def base_attrs(self, target: Class) -> List[Attr]:
    attrs: List[Attr] = []
    for extension in target.extensions:
        base = self.container.find(extension.type.qname)
        assert (base is not None)
        attrs.extend(base.attrs)
        attrs.extend(self.base_attrs(base))
    return attrs
def base_attrs(self, target: Class) -> List[Attr]:
    attrs: List[Attr] = []
    for extension in target.extensions:
        base = self.container.find(extension.type.qname)
        assert (base is not None)
        attrs.extend(base.attrs)
        attrs.extend(self.base_attrs(base))
    return attrs