code: def fork(self,name):
          '''
          Create fork and store it in current instance
          '''
          fork=deepcopy(self)
          self[name]=fork
          return forf fork(self,name):
          '''
          Create fork and store it in current instance
          '''
          fork=deepcopy(self)
          self[name]=fork
          return fork
docs: Create fork and store it in current instance