Handle slices

Author: alejoe91

neo/rawio/axonarawio.py

@@ -302,8 +302,11 @@ def _get_analogsignal_chunk(self, block_index, seg_index, i_start, i_stop,
             i_start = 0
         if i_stop is None:
             i_stop = bin_dict['num_total_samples']
-        if channel_indexes is None or isinstance(channel_indexes, slice):
+        if channel_indexes is None:
             channel_indexes = [i for i in range(bin_dict['num_channels'])]
+        if isinstance(channel_indexes, slice):
+            channel_indexes_all = [i for i in range(bin_dict['num_channels'])]
+            channel_indexes = channel_indexes_all[channel_indexes]
 
         num_samples = (i_stop - i_start)