code: def body(self, definitions, body, root):
          
          if root is None:
              body.use = 'literal'
              body.namespace = definitions.tns
              body.parts = ()
              return
          parts = root.get('parts')
          if parts is None:
              body.parts = ()
          else:
              body.parts = re.split('[\s,]', parts)
          body.use = root.get('use', default='literal')
          ns = root.get('namespace')
          if ns is None:
              body.namespace = definitions.tns
          else:
              prefix = root.findPrefix(ns, 'b0')
              body.namespace = (prefix, ns)
docs: add the input/output body properties