is_dask_collection: micro optimization (#6107)

Author: mathause

xarray/core/pycompat.py

@@ -43,8 +43,19 @@ def __init__(self, mod):
         self.available = duck_array_module is not None
 
 
+dsk = DuckArrayModule("dask")
+dask_version = dsk.version
+dask_array_type = dsk.type
+
+sp = DuckArrayModule("sparse")
+sparse_array_type = sp.type
+sparse_version = sp.version
+
+cupy_array_type = DuckArrayModule("cupy").type
+
+
 def is_dask_collection(x):
-    if DuckArrayModule("dask").available:
+    if dsk.available:
         from dask.base import is_dask_collection
 
         return is_dask_collection(x)
@@ -54,14 +65,3 @@ def is_dask_collection(x):
 
 def is_duck_dask_array(x):
     return is_duck_array(x) and is_dask_collection(x)
-
-
-dsk = DuckArrayModule("dask")
-dask_version = dsk.version
-dask_array_type = dsk.type
-
-sp = DuckArrayModule("sparse")
-sparse_array_type = sp.type
-sparse_version = sp.version
-
-cupy_array_type = DuckArrayModule("cupy").type