修改判断空域的bug
diff --git a/supwisdom/protocol/nettrans.py b/supwisdom/protocol/nettrans.py
index 98099f7..6ecac96 100644
--- a/supwisdom/protocol/nettrans.py
+++ b/supwisdom/protocol/nettrans.py
@@ -171,7 +171,7 @@
         """

         assert self._row_no >= 0

         arg = self._row_data[self._row_no].get(name, None)

-        if not arg:

+        if arg is None:

             if strip and default == message_reader._ARG_DEFAULT:

                 raise IndexError(u'no such column %s' % name)

             return default