code: def qn(tag):
      
      prefix, tagroot = tag.split(':')
      uri = nsmap[prefix]
      return '{%s}%s' % (uri, tagroot)
docs: Stands for "qualified name", a utility function to turn a namespace
      prefixed tag name into a Clark-notation qualified tag name for lxml. For
      example, ``qn('p:cSld')`` returns ``'{http://schemas.../main}cSld'``.