Load ticker list from txt file

def get_tickers_from_file(self, filename):
        """Load ticker list from txt file"""
        if not os.path.exists(filename):
            log.error("Ticker List file does not exist: %s", filename)

        tickers = []
        with io.open(filename, 'r') as fd:
            for ticker in fd:
                tickers.append(ticker.rstrip())
        return tickers