'Update statistics after lemmas and stems have been set.'

def update(self):

    (self.gumt, self.gdmt, self.gwmt, self.gdnt) = _calculate(self.lemmas, self.stems)
    (self.ui, self.oi, self.sw) = _indexes(self.gumt, self.gdmt, self.gwmt, self.gdnt)
    self.errt = self._errt()
