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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 _filter_child_model_fields(cls, fields):
 """ Keep only related model fields. Example: Inherited models: A -> B -> C B has one-to-many relationship to BMany. after inspection BMany would have links to B and C. Keep only B. Parent model A could not be used (It would not be in fields) :param list fields: model fields. :return list fields: filtered fields. """

        indexes_to_remove = set([])
        for index1, field1 in enumerate(fields):
            for index2, field2 in enumerate(fields):
                if index1 < index2 and index1 not in indexes_to_remove and\
                        index2 not in indexes_to_remove:
                    if issubclass(field1.related_model, field2.related_model):
                        indexes_to_remove.add(index1)

                    if issubclass(field2.related_model, field1.related_model):
                        indexes_to_remove.add(index2)

        fields = [field for index, field in enumerate(fields)
                  if index not in indexes_to_remove]

        return fields