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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 fetch(cls, client, _id, symbol):
 """ fetch option chain for instrument """

        url = "https://api.robinhood.com/options/chains/"
        params = {
            "equity_instrument_ids": _id,
            "state": "active",
            "tradability": "tradable"
        }
        data = client.get(url, params=params)

        def filter_func(x):
            return x["symbol"] == symbol
        results = list(filter(filter_func, data["results"]))
        return results[0]