code: def resolveport(self, definitions):
          
          ref = qualify(self.type, self.root, definitions.tns)
          port_type = definitions.port_types.get(ref)
          if port_type is None:
              raise Exception("portType '%s', not-found" % self.type)
          else:
              self.type = port_type
docs: Resolve port_type reference.
          @param definitions: A definitions object.
          @type definitions: L{Definitions}