--- a/svgui/pyjs/pyjs.py	Wed Oct 10 10:32:57 2018 +0300
+++ b/svgui/pyjs/pyjs.py	Wed Oct 10 10:36:07 2018 +0300
@@ -23,6 +23,7 @@
 import os
 import copy
 from builtins import str as text
+from past.builtins import basestring
 from six.moves import cStringIO
 
 # the standard location for builtins (e.g. pyjslib) can be

--- a/tests/tools/check_source.sh	Wed Oct 10 10:32:57 2018 +0300
+++ b/tests/tools/check_source.sh	Wed Oct 10 10:36:07 2018 +0300
@@ -364,6 +364,7 @@
     enable=$enable,W1607          # (file-builtin) file built-in referenced
     enable=$enable,W1606          # (execfile-builtin) execfile built-in referenced
     enable=$enable,W1629          # (nonzero-method) __nonzero__ method defined
+    enable=$enable,W1602          # (basestring-builtin) basestring built-in referenced
     # enable=
 
     options=