Okay, I guess it was easier to replace it in 4f47c529cc6069a680e66c4a1b52b342b8be02dc. Why not write a helper function

```diff
diff --git a/test/test_read.py b/test/test_read.py
index dacc521..3822201 100644
--- a/test/test_read.py
+++ b/test/test_read.py
@@ -2,7 +2,7 @@
 import unittest

 from . import horror_fobj
-from nose.tools import assert_equal, assert_is_instance, assert_true
+from nose.tools import assert_equal, assert_true

 from messytables import (CSVTableSet, StringType, HTMLTableSet,
                          ZIPTableSet, XLSTableSet, XLSXTableSet, PDFTableSet,
@@ -13,6 +13,12 @@ from messytables import (CSVTableSet, StringType, HTMLTableSet,
 import datetime
 import warnings

+try:
+    from nose.tools import assert_is_instance
+except ImportError:
+    def assert_is_instance(obj, cls, msg=None):
+        assert_true(isinstance(obj, cls))
+

 class ReadCsvTest(unittest.TestCase):
     def test_read_simple_csv(self):
```