Now that it\'s clear what a metaclass is, there is an associated concept that I use all the time without knowing what it really means.
I suppose everybody made once
Callable is a type or class of "Build-in function or Method" with a method call
>>> type(callable)
>>>
Example: print is a callable object. With a build-in function __call__ When you invoke the print function, Python creates an object of type print and invokes its method __call__ passing the parameters if any.
>>> type(print)
>>> print.__call__(10)
10
>>> print(10)
10
>>>
Thank you. Regards, Maris