Polish

Common/util_eddies.py

@@ -220,6 +220,8 @@ class SHPC_class:
         try:
             i_slice = self._i_slice[date_index - self.d_init[0]]
         except IndexError:
+            # This can happen in particular if date_index=d_init[0]
+            # and all the slices have empty date ranges.
             i_slice = None
 
         return i_slice