From b14fbd9394a6195680150327d3c10fcb176bbc5f Mon Sep 17 00:00:00 2001
From: Maximilian Roos <5635139+max-sixty@users.noreply.github.com>
Date: Sat, 23 Sep 2023 12:38:05 -0700
Subject: [PATCH] Add a `Literal` typing (#8227)

* Add a `Literal` typing
---
 xarray/core/computation.py       | 2 +-
 xarray/tests/test_computation.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/xarray/core/computation.py b/xarray/core/computation.py
index 971f036b394..bae779af652 100644
--- a/xarray/core/computation.py
+++ b/xarray/core/computation.py
@@ -893,7 +893,7 @@ def apply_ufunc(
     dataset_fill_value: object = _NO_FILL_VALUE,
     keep_attrs: bool | str | None = None,
     kwargs: Mapping | None = None,
-    dask: str = "forbidden",
+    dask: Literal["forbidden", "allowed", "parallelized"] = "forbidden",
     output_dtypes: Sequence | None = None,
     output_sizes: Mapping[Any, int] | None = None,
     meta: Any = None,
diff --git a/xarray/tests/test_computation.py b/xarray/tests/test_computation.py
index b75e80db2da..87f8328e441 100644
--- a/xarray/tests/test_computation.py
+++ b/xarray/tests/test_computation.py
@@ -1190,7 +1190,7 @@ def test_apply_dask() -> None:
 
     # unknown setting for dask array handling
     with pytest.raises(ValueError):
-        apply_ufunc(identity, array, dask="unknown")
+        apply_ufunc(identity, array, dask="unknown")  # type: ignore
 
     def dask_safe_identity(x):
         return apply_ufunc(identity, x, dask="allowed")