为什么递增的值在循环结束后变为null？

Question

V_TOTAL_SIZE_MB值在循环内，但是当我尝试打印时V_TOTAL_SIZE_GB在循环后或循环内变为空。

--- python2.7/site-packages/suds/client.py Sun Jan 08 16:58:36 2017 +0100
+++ client.py Thu Oct 05 11:04:20 2017 +0200
@@ -631,7 +631,8 @@
             else:
                 soapenv = soapenv.plain()
             soapenv = soapenv.encode('utf-8')
-            plugins.message.sending(envelope=soapenv)
+            ctx = plugins.message.sending(envelope=soapenv)
+            soapenv = ctx.envelope
             request = Request(location, soapenv)
             request.headers = self.headers()
             reply = transport.send(request)