当我执行这段代码时，程序会生成[None, None, None,...]
我期待烛台图
import matplotlib.finance as mpf
import matplotlib.pyplot as plt
start =(2014,5,1)
end = (2014,6,30)
quotes = mpf.quotes_historical_yahoo_ochl('^GDAXI',start, end)
fig, ax=plt.subplots(figsize=(8,5))
fig.subplots_adjust(bottom=0.2)
mpf.candlestick_ochl(ax,quotes,width=0.6,colorup='b',colordown='r')
plt.grid(True)
ax.xaxis_date()
ax.autoscale_view()
plt.setp(plt.gca().get_xticklabels(),rotation=30)