def abstractmethod(funcobj):
funcobj.__isabstractmethod__ = True<EOL>return funcobj<EOL>
A decorator indicating abstract methods.

    Requires that the metaclass is ABCMeta or derived from it.  A
    class that has a metaclass derived from ABCMeta cannot be
    instantiated unless all of its abstract methods are overridden.
    The abstract methods can be called using any of the normal
    'super' call mechanisms.

    Usage:

        class C:
            __metaclass__ = ABCMeta
            @abstractmethod
            def my_abstract_method(self, ...):
                ...