autoload 3 modules if using 3

tablib/formats/_html.py

@@ -3,9 +3,15 @@
 """ Tablib - HTML export support.
 """
 
+import sys
 from io import StringIO
 
-from tablib.packages import markup
+
+if sys.version_info.major > 2:
+    from tablib.packages import markup3 as markup
+else:
+    from tablib.packages import markup
+
 import tablib
 
 BOOK_ENDINGS = 'h3'

tablib/formats/_yaml.py

@@ -3,10 +3,16 @@
 """ Tablib - YAML Support.
 """
 
+import sys
+
 try:
     import yaml
 except ImportError:
-    import tablib.packages.yaml as yaml
+    if sys.version_info.major > 2:
+        import tablib.packages.yaml3 as yaml
+    else:
+        import tablib.packages.yaml as yaml
+    
 
 import tablib
 

test_tablib.py

@@ -4,8 +4,14 @@
 """Tests for Tablib."""
 
 import unittest
+import sys
+
+if sys.version_info.major > 2:
+    from tablib.packages import markup3 as markup
+else:
+    from tablib.packages import markup
+
 
-from tablib.packages import markup
 
 import tablib