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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_custom_value(self, field_name):
 """ Get a value for a specified custom field field_name - Name of the custom field you want. """

        custom_field = self.get_custom_field(field_name)
        return CustomFieldValue.objects.get_or_create(
            field=custom_field, object_id=self.id)[0].value