def METHOD_NAME(self):
    # the "Zope Book" describes ``CONTEXTS`` as a variable.
    # But, in fact, it is not a (regular) variable but a special
    # case of the initial component of a (sub)path expression.
    # As a consequence, it cannot be used in a Python expression
    # but only as the first component in a path expression
    # Therefore, we cannot use ``check`` to access it.
    t = self.g.t
    t.write("""<div tal:define="
            x CONTEXTS;
            dummy python:options['acc'].append(x)" />""")
    acc = []
    t(acc=acc)
    ctx = acc[0]
    self.assertIsInstance(ctx, dict)
    # all variables included?
    self.assertEqual(len(self.VARIABLES - set(ctx)), 0)