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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 decode_sql(self, sql):
 """Base64 decode a string. This should only be used for sql in calls. :param str sql: The base64 encoded form of the original utf-8 string :return str: The decoded utf-8 string """

        # JSON is defined as using "unicode", we'll go a step further and
        # mandate utf-8 (though for the base64 part, it doesn't really matter!)
        base64_sql_bytes = to_unicode(sql).encode('utf-8')
        # in python3.x you can pass `validate=True` to b64decode to get this
        # behavior.
        if not re.match(b'^[A-Za-z0-9+/]*={0,2}$', base64_sql_bytes):
            self.raise_invalid_base64(sql)

        try:
            sql_bytes = base64.b64decode(base64_sql_bytes)
        except ValueError:
            self.raise_invalid_base64(sql)

        return sql_bytes.decode('utf-8')