TypeError in Python when using Pyalgotrade

I trying to write a Stochcastic Oscillator in python using the list function in Pyalgotrade library.

My code is below:

from pyalgotrade.tools import yahoofinance
from pyalgotrade import strategy
from pyalgotrade.barfeed import yahoofeed
from pyalgotrade.technical import stoch
from pyalgotrade import dataseries
from pyalgotrade.technical import ma
from pyalgotrade import technical
from pyalgotrade.technical import highlow
from pyalgotrade import bar
from pyalgotrade.talibext import indicator
import numpy
import talib

class MyStrategy(strategy.BacktestingStrategy):
    def __init__(self, feed, instrument):
        strategy.BacktestingStrategy.__init__(self, feed)  
        self.__instrument = instrument

    def onBars(self, bars):

        barDs = self.getFeed().getDataSeries("002389.SZ")

        self.__stoch = indicator.STOCH(barDs, 20, 3, 3)

        bar = bars[self.__instrument]
        self.info("%0.2f, %0.2f" % (bar.getClose(), self.__stoch[-1]))

# Downdload then Load the yahoo feed from the CSV file
yahoofinance.download_daily_bars('002389.SZ', 2013, '002389.csv')
feed = yahoofeed.Feed()
feed.addBarsFromCSV("002389.SZ", "002389.csv")

# Evaluate the strategy with the feed's bars.
myStrategy = MyStrategy(feed, "002389.SZ")
myStrategy.run()

And I got the error like this:

  File "/Users/johnhenry/Desktop/simple_strategy.py", line 46, in onBars
    self.info("%0.2f, %0.2f" % (bar.getClose(), self.__stoch[-1]))
TypeError: float argument required, not numpy.ndarray

Stochastic:

pyalgotrade.talibext.indicator.STOCH(barDs, count, fastk_period=-2147483648, slowk_period=-2147483648, slowk_matype=0, slowd_period=-2147483648, slowd_matype=0)

Either bar.getClose() or self.__stoch[-1] is returning a numpy.ndarray while both should be returning floats.