Patch: improve type hint (langchain-ai#15451)

Author: chyroc

libs/community/langchain_community/utilities/sql_database.py

@@ -2,7 +2,7 @@
 from __future__ import annotations
 
 import warnings
-from typing import Any, Dict, Iterable, List, Literal, Optional, Sequence, Union
+from typing import Any, Dict, Iterable, List, Literal, Optional, Sequence
 
 import sqlalchemy
 from langchain_core.utils import get_from_env
@@ -376,14 +376,14 @@ def _get_sample_rows(self, table: Table) -> str:
     def _execute(
         self,
         command: str,
-        fetch: Union[Literal["all"], Literal["one"]] = "all",
+        fetch: Literal["all", "one"] = "all",
     ) -> Sequence[Dict[str, Any]]:
         """
         Executes SQL command through underlying engine.
 
         If the statement returns no rows, an empty list is returned.
         """
-        with self._engine.begin() as connection:
+        with self._engine.begin() as connection:  # type: Connection
             if self._schema is not None:
                 if self.dialect == "snowflake":
                     connection.exec_driver_sql(
@@ -426,7 +426,7 @@ def _execute(
     def run(
         self,
         command: str,
-        fetch: Union[Literal["all"], Literal["one"]] = "all",
+        fetch: Literal["all", "one"] = "all",
         include_columns: bool = False,
     ) -> str:
         """Execute a SQL command and return a string representing the results.
@@ -471,7 +471,7 @@ def get_table_info_no_throw(self, table_names: Optional[List[str]] = None) -> st
     def run_no_throw(
         self,
         command: str,
-        fetch: Union[Literal["all"], Literal["one"]] = "all",
+        fetch: Literal["all", "one"] = "all",
         include_columns: bool = False,
     ) -> str:
         """Execute a SQL command and return a string representing the results.

libs/core/langchain_core/prompts/few_shot.py

@@ -98,7 +98,7 @@ def is_lc_serializable(cls) -> bool:
     prefix: str = ""
     """A prompt template string to put before the examples."""
 
-    template_format: Union[Literal["f-string"], Literal["jinja2"]] = "f-string"
+    template_format: Literal["f-string", "jinja2"] = "f-string"
     """The format of the prompt template. Options are: 'f-string', 'jinja2'."""
 
     @root_validator()

libs/core/langchain_core/prompts/prompt.py

@@ -65,7 +65,7 @@ def get_lc_namespace(cls) -> List[str]:
     template: str
     """The prompt template."""
 
-    template_format: Union[Literal["f-string"], Literal["jinja2"]] = "f-string"
+    template_format: Literal["f-string", "jinja2"] = "f-string"
     """The format of the prompt template. Options are: 'f-string', 'jinja2'."""
 
     validate_template: bool = False