docs: def _persist_inplace(self, **kwargs):
          """ Persist all Dask arrays in memory """
          # access .data to coerce everything to numpy or dask arrays
          lazy_data = {k: v._data for k, v in self.variables.items()
                       if isinstance(v._data, dask_array_type)}
          if lazy_data:
              import dask
  
              # evaluate all the dask arrays simultaneously
              evaluated_data = dask.persist(*lazy_data.values(), **kwargs)
  
              for k, data in zip(lazy_data, evaluated_data):
                  self.variables[k].data = data
  
          return self