title: Python Suds error "ns (None) not mapped"
body: <p>I<code>m not familiar with</code>WSDL<code>and</code>XSD<code>, my problem with Suds is the following:
  According to Sud</code>s documentation I am trying to create a client object - </p>
  
  <pre><code>url = "http://192.168.1.21/crs/RateService.svc?singleWsdl"
  client = Client(url)
  </code></pre>
  
  <p>but after </p>
  
  <pre><code>print client
  </code></pre>
  
  <p>I had an issue:</p>
  
  <pre><code>Suds ( https://fedorahosted.org/suds/ )  version: 0.4 GA  build: R699-20100913
  
  ns (None) not mapped
  </code></pre>
  
  <p>in debug log I found that (in the end of file):</p>
  
  <pre><code>DEBUG:suds.xsd.query:TypeQuery:0x7f7528743050, found builtin (dateTime)
  ERROR:suds.servicedefinition:ns (None) not mapped
  Traceback (most recent call last):
    File "/usr/local/lib/python2.7/dist-packages/suds/servicedefinition.py", line 245, in __unicode__
      return self.description()
    File "/usr/local/lib/python2.7/dist-packages/suds/servicedefinition.py", line 236, in description
      s.append(self.xlate(t[0]))
    File "/usr/local/lib/python2.7/dist-packages/suds/servicedefinition.py", line 193, in xlate
      prefix = self.getprefix(ns[1])
    File "/usr/local/lib/python2.7/dist-packages/suds/servicedefinition.py", line 176, in getprefix
      raise Exception('ns (%s) not mapped'  % u)
  Exception: ns (None) not mapped
  </code></pre>
  
  <p>Any ideas? </p>