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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_record_fields(d):
 """Get field names from a potentially nested record. """

    if isinstance(d, dict):
        if "fields" in d:
            return d["fields"]
        else:
            for v in d.values():
                fields = _get_record_fields(v)
                if fields:
                    return fields