Merge pull request #246 from INM-6/fix/nonetype_check

Updating check for NoneType by using "is" instead of "=="

Author: apdavison

neo/core/analogsignal.py

@@ -560,15 +560,15 @@ def time_slice(self, t_start, t_stop):
         '''
 
         # checking start time and transforming to start index
-        if t_start == None:
+        if t_start is None:
             i = 0
         else:
             t_start = t_start.rescale(self.sampling_period.units)
             i = (t_start - self.t_start) / self.sampling_period
             i = int(np.rint(i.magnitude))
 
         # checking stop time and transforming to stop index
-        if t_stop == None:
+        if t_stop is None:
             j = len(self)
         else:
             t_stop = t_stop.rescale(self.sampling_period.units)