(The deleted example no longer works and is thus irrelevant.)
.. note::
:func:`runtime_checkable` will check only the presence of the required methods,
- not their type signatures! For example, :class:`builtins.complex <complex>`
- implements :func:`__float__`, therefore it passes an :func:`issubclass` check
- against :class:`SupportsFloat`. However, the ``complex.__float__`` method
- exists only to raise a :class:`TypeError` with a more informative message.
+ not their type signatures.
.. versionadded:: 3.8