code: def unhandle(self, handler):
          
          h, _, _ = self._extract(handler)
          key = hash(h)
          with self._hlock:
              if key not in self.handlers:
                  raise ValueError('Handler "%s" was not found' % str(h))
              handlers = self.handlers.copy()
              del handlers[key]
              self.handlers = handlers
          return self
docs: Unregisters a handler