wip operator: modified Self import

Author: ym-pett

narwhals/_sql/expr.py

@@ -500,7 +500,7 @@ def round(self, decimals: int) -> Self:
     def sqrt(self) -> Self:
         def _sqrt(expr: NativeSQLExprT) -> NativeSQLExprT:
             return self._when(
-                expr < self._lit(0),  
+                expr < self._lit(0),  # type: ignore[operator]
                 self._lit(float("nan")),
                 self._function("sqrt", expr),
             )

narwhals/_sql/typing.py

@@ -1,13 +1,14 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any, TypeVar, Self
+from typing import TYPE_CHECKING, Any, TypeVar
 
 from narwhals._compliant.expr import NativeExpr
 
 if TYPE_CHECKING:
     from narwhals._sql.dataframe import SQLLazyFrame
     from narwhals._sql.expr import SQLExpr
     from narwhals.dtypes import Boolean
+    from typing_extensions import Self
 
     # TODO: @mp, understand why these are here & if we need one for NativeSQLExprT
     SQLExprAny = SQLExpr[Any, Any]