Multiple vspan's on time series chart

r_SP500 = quandl.get(“YAHOO/INDEX_GSPC.4”)
r_SP500 = np.log(r_SP500)
r_SP500.iplot(theme = ‘white’, kind=‘line’, fill=False, legend=True, yTitle=‘Close Price (Log)’, vspan={‘x0’:‘1950-06-12’,‘x1’:‘1950-07-17’,‘color’:‘rgba(30,30,30,0.3)’,‘fill’:True,‘opacity’:.4}, title=‘S&P 500’, filename=‘cufflinks/stock dataSP500’)