internal function that gives absolute_spike_times_from_labels, as well as 
            the factor (maximum range)

def _absolute_spike_times_from_labels(self,time_dimension=0,*args,**kwargs):
        """
            internal function that gives absolute_spike_times_from_labels, as well as 
            the factor (maximum range)
        """
        x = self[time_dimension].copy()
        #x = self.spike_times.get_converted(time_dimension,kwargs.get('units',None))
        factor = self.len(time_dimension,units=kwargs.get('units',None),resolution=kwargs.get('resolution',1.0))
        for a in args:
            if a in self:
                x += factor * self[a]
                factor *= self.len(a)
        for k in kwargs.keys():
            if k in self:
                x += factor * self[k]
                if kwargs[k] is not None:
                    factor *= kwargs[k]
                else:
                    factor *= self.len(k)
        return x,factor