How to draw the data with histgram.

[peacerider]

I am now creating strategy using MACD.
So I would like to draw the MACD histogram as the plot type of histogram instead of a line.

Now, I can draw with plot of line.

from backtesting import Backtest, Strategy
from backtesting.lib import crossover
from backtesting.test import SMA, GOOG
import talib as ta

# MACD
def macd_macd(close, n1, n2, ns):
    macd, macdsignal, macdhist = ta.MACD(close, fastperiod=n1, slowperiod=n2, signalperiod=ns)
    return macd

def macd_signal(close, n1, n2, ns):
    macd, macdsignal, macdhist = ta.MACD(close, fastperiod=n1, slowperiod=n2, signalperiod=ns)
    return macdsignal

def macd_hist(close, n1, n2, ns):
    macd, macdsignal, macdhist = ta.MACD(close, fastperiod=n1, slowperiod=n2, signalperiod=ns)
    return macdhist

class SmaCross(Strategy):
    n1 = 10
    n2 = 20
    fast = 12
    slow = 26
    signal = 9

    def init(self):
        close = self.data.Close
        self.sma1 = self.I(SMA, close, self.n1)
        self.sma2 = self.I(SMA, close, self.n2)
        
        self.macd_ = macd_macd(close, self.fast, self.slow, self.signal)
        self.macdsignal_ = macd_signal(close, self.fast, self.slow, self.signal)
        
        self.macd, self.macdsignal = self.I(lambda: (self.macd_, self.macdsignal_), name="MACD")
        self.macdhist = self.I(macd_hist, close, self.fast, self.slow, self.signal, name="MACD Histgram")
        
    def next(self):
        if crossover(self.sma1, self.sma2):
            self.buy()
        elif crossover(self.sma2, self.sma1):
            self.sell()

bt = Backtest(GOOG, SmaCross,
              cash=10000, commission=.002,
              exclusive_orders=True)

output = bt.run()
bt.plot()