nits

Author: crusaderky

array_api_compat/common/_helpers.py

@@ -903,7 +903,14 @@ def __getitem__(self, idx):
         self.idx = idx
         return self
 
-    def _common(self, at_op, y=_undef, mode: str = "promise_in_bounds", **kwargs):
+    def _common(
+        self,
+        at_op: str,
+        y=_undef,
+        copy: bool | None = True, 
+        mode: str = "promise_in_bounds", 
+        **kwargs,
+    ):
         """Validate kwargs and perform common prepocessing.
 
         Returns
@@ -1028,7 +1035,7 @@ def max(self, y, /, **kwargs):
         xp = array_namespace(self.x)
         return self._iop("max", xp.maximum, y, **kwargs)
 
-def where(condition, x, y, /, copy: bool | None = True):
+def where(condition, x=None, y=None, /, copy: bool | None = True):
     """Return elements from x when condition is True and from y when
     it is False. 
 
@@ -1043,6 +1050,10 @@ def where(condition, x, y, /, copy: bool | None = True):
     False
         Raise ValueError if a copy cannot be avoided.
     """
+    if x is None and y is None:
+        xp = array_namespace(condition)
+        return xp.where(condition)
+
     copy = _parse_copy_param(x, copy)
     xp = array_namespace(condition, x, y)
     if copy: