version = Nonewith open(join(here, "html5lib", "__init__.py"), "rb") as init_file:    t = ast.parse(init_file.read(), filename="__init__.py", mode="exec")    assert isinstance(t, ast.Module)    assignments = filter(lambda x: isinstance(x, ast.Assign), t.body)    for a in assignments:        if (len(a.targets) == 1 and                isinstance(a.targets[0], ast.Name) and                a.targets[0].id == "__version__"):            if hasattr(ast, "Str") and isinstance(a.value, ast.Str):                version = a.value.s            elif (hasattr(ast, "Constant")                  and isinstance(a.value, ast.Constant)                  and isinstance(a.value.value, str)):                version = a.value.valueassert version is not None