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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 serialize_compound(self, tag):
 """Return the literal representation of a compound tag."""

        separator, fmt = self.comma, '{{{}}}'

        with self.depth():
            if self.should_expand(tag):
                separator, fmt = self.expand(separator, fmt)

            return fmt.format(separator.join(
                f'{self.stringify_compound_key(key)}{self.colon}{self.serialize(value)}'
                for key, value in tag.items()
            ))