python meta subclass

meta.py

class MyMeta(type):
    def __new__(mcs, name, bases, clsdict):

        clsdict['fields'] = {k: v
                             for k, v in clsdict.items()
                             if not k.startswith("_")}
        return super(MyMeta, mcs).__new__(mcs, name, bases, clsdict)

class MyBaseClass(metaclass=MyMeta):
    fields = {}

class SubClass(MyBaseClass):
    param1 = 1 # meets <my_condition>

class SubSubClass(MyBaseClass):
    pass


if __name__ == "__main__":
    print("SubClass.fields: (expect {'param1': 1})"
    print(SubClass.fields)
    print("SubSubClass.fields: (expect {'param1': 1})"   
    print(SubSubClass.fields)