Update README.md

README.md

@@ -14,6 +14,8 @@ It comes in three splits: `train`, `eval` and `test`.
 To open a `train` split of the dataset and show an `elevation` plot at `time=2137`:
 
 ```python
+import xarray as xr
+
 ds = xr.open_zarr("train.zarr")
 ds["elevation"].sel(time=2137).plot.imshow(origin="upper")
 ```