"DOC #45443 edited the documentation of where/mask functions"

pandas/core/generic.py

@@ -9571,6 +9571,8 @@ def where(
         cond : bool {klass}, array-like, or callable
             Where `cond` is {cond}, keep the original value. Where
             {cond_rev}, replace with corresponding value from `other`.
+            if `cond` {klass} is less in size than `other`, the default bool
+            for the missing value is {cond_rev}.
             If `cond` is callable, it is computed on the {klass} and
             should return boolean {klass} or array. The callable must
             not change input {klass} (though pandas doesn't check it).