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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def get_property_names(self):
        '''
        Returns all property names in this collection of signatures
        '''
        property_names = set()
        for signature_value in self.values():
            for property_name in signature_value.keys():
                property_names.add(property_name)
        return property_names