1.0 leverage.py error
如果成交後，本金不變，會触發0/self._value error。
2.0 debug
def next(self):
# Updates the leverage for "dtkey" (see base class) for each cycle
# 0.0 if 100% in cash, 1.0 if no short selling and fully invested
try:
lev = (self._value - self._cash) / self._value
except:
lev = 0
self.rets[self.data0.datetime.datetime()] = lev
leverage.py，line 61~74。