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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 prepare_fields_attribute(attribute_name, attributes, class_name):
 """Prepare model fields attribute."""

        attribute = attributes.get(attribute_name)
        if not attribute:
            attribute = tuple()
        elif isinstance(attribute, std_collections.Iterable):
            attribute = tuple(attribute)
        else:
            raise errors.Error('{0}.{1} is supposed to be a list of {2}, '
                               'instead {3} given', class_name, attribute_name,
                               fields.Field, attribute)
        return attribute