I want to have only ONE function exists in the root class, and it seems only one OUR variable exists in the root class is not a good solution, because it will be affected by all of its descendants. What I want is:

Foo: get Base and Foo
Bar: get Base and Bar
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but not:

Foo: get Base, Foo and Bar
Bar: get Base, Foo and Bar
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It seems that I have to write a sub recursively traverse through the namespace tree?