'Subscribes the price handler to a new ticker symbol.'

def subscribe_ticker(self, ticker):

    if (ticker not in self.tickers):
        try:
            self._open_ticker_price_csv(ticker)
            dft = self.tickers_data[ticker]
            row0 = dft.iloc[0]
            close = PriceParser.parse(row0['Close'])
            ticker_prices = {'close': close, 'adj_close': close, 'timestamp': dft.index[0]}
            self.tickers[ticker] = ticker_prices
        except OSError:
            print ('Could    not    subscribe    ticker    %s    as    no    data    CSV    found    for    pricing.' % ticker)
    else:
        print ('Could    not    subscribe    ticker    %s    as    is    already    subscribed.' % ticker)
