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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 _validate_overriden_fields_are_not_defined_in_superclasses(class_to_field_type_overrides, schema_graph):
 """Assert that the fields we want to override are not defined in superclasses."""

    for class_name, field_type_overrides in six.iteritems(class_to_field_type_overrides):
        for superclass_name in schema_graph.get_inheritance_set(class_name):
            if superclass_name != class_name:
                superclass = schema_graph.get_element_by_class_name(superclass_name)
                for field_name in field_type_overrides:
                    if field_name in superclass.properties:
                        raise AssertionError(
                            u'Attempting to override field "{}" from class "{}", but the field is '
                            u'defined in superclass "{}"'
                            .format(field_name, class_name, superclass_name))