code: def ref(self):
          
  
          x = RefTrace(self.filehandle,
                       self.dtype,
                       len(self),
                       self.shape,
                       self.readonly,
                      )
          yield x
          x.flush()
docs: A write-back version of Trace
  
          Returns
          -------
          ref : RefTrace
              `ref` is returned in a context manager, and must be in a ``with``
              statement
  
          Notes
          -----
          .. versionadded:: 1.6
  
          Examples
          --------
          >>> with trace.ref as ref:
          ...     ref[10] += 1.617