Negative index processing moved to a method

src/widgetastic/widget.py

@@ -1322,17 +1322,20 @@ def assoc_column_position(self):
             raise TypeError(
                 'Wrong type passed for assoc_column= : {}'.format(type(self.assoc_column).__name__))
 
+    def _process_negative_index(self, nindex):
+        """The semantics is pretty much the same like for ordinary list."""
+        rc = self.row_count
+        if (- nindex) > rc:
+            raise ValueError(
+                'Negative index {} wanted but we only have {} rows'.format(nindex, rc))
+        return rc + nindex
+
     def __getitem__(self, at_index):
         if not isinstance(at_index, int):
             raise TypeError('table indexing only accepts integers')
         if at_index < 0:
             # Row class cannot handle negative indices, so we need to convert it ourselves.
-            # The semantics is pretty much the same like for ordinary list.
-            rc = self.row_count
-            if (- at_index) > rc:
-                raise ValueError(
-                    'Negative index {} wanted but we only have {} rows'.format(at_index, rc))
-            at_index = rc + at_index
+            at_index = self._process_negative_index(at_index)
         return self.Row(self, at_index, logger=self.logger)
 
     def row(self, *extra_filters, **filters):