<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def fill_default(self):
 """ Define the object properties with a default value when the property is not yet defined :return: None """

        for prop, entry in self.__class__.properties.items():
            if hasattr(self, prop):
                continue
            if not hasattr(entry, 'default') or entry.default is NONE_OBJECT:
                continue

            if hasattr(entry.default, '__iter__'):
                setattr(self, prop, copy(entry.default))
            else:
                setattr(self, prop, entry.default)