def METHOD_NAME(data, params):
    length = len(data.ETH_price)
    ETH_price_past = None
    if (params.lookback > length):
        ETH_price_past = data.ETH_price[0]
    else:
        ETH_price_past = data.ETH_price[length - params.lookback - 1]
    if ETH_price_past == 0:
        return 1
    return ETH_price_past