core: chat_* docstrings (#23412)

Added missed docstrings. Formatted docstrings to the consistent form.

libs/core/langchain_core/chat_history.py

@@ -14,6 +14,7 @@
     AIMessage, HumanMessage, BaseMessage
 
 """  # noqa: E501
+
 from __future__ import annotations
 
 from abc import ABC, abstractmethod
@@ -144,6 +145,10 @@ class BaseChatMessageHistory(ABC):
 
         Args:
             message: A BaseMessage object to store.
+
+        Raises:
+            NotImplementedError: If the sub-class has not implemented an efficient
+                add_messages method.
         """
         if type(self).add_messages != BaseChatMessageHistory.add_messages:
             # This means that the sub-class has implemented an efficient add_messages
@@ -162,16 +167,16 @@ class BaseChatMessageHistory(ABC):
         in an efficient manner to avoid unnecessary round-trips to the underlying store.
 
         Args:
-            messages: A list of BaseMessage objects to store.
+            messages: A sequence of BaseMessage objects to store.
         """
         for message in messages:
             self.add_message(message)
 
     async def aadd_messages(self, messages: Sequence[BaseMessage]) -> None:
-        """Add a list of messages.
+        """Async add a list of messages.
 
         Args:
-            messages: A list of BaseMessage objects to store.
+            messages: A sequence of BaseMessage objects to store.
         """
         from langchain_core.runnables.config import run_in_executor
 
@@ -182,7 +187,7 @@ class BaseChatMessageHistory(ABC):
         """Remove all messages from the store"""
 
     async def aclear(self) -> None:
-        """Remove all messages from the store"""
+        """Async remove all messages from the store"""
         from langchain_core.runnables.config import run_in_executor
 
         await run_in_executor(None, self.clear)
@@ -199,20 +204,24 @@ class InMemoryChatMessageHistory(BaseChatMessageHistory, BaseModel):
     """
 
     messages: List[BaseMessage] = Field(default_factory=list)
+    """A list of messages stored in memory."""
 
     async def aget_messages(self) -> List[BaseMessage]:
+        """Async version of getting messages."""
         return self.messages
 
     def add_message(self, message: BaseMessage) -> None:
-        """Add a self-created message to the store"""
+        """Add a self-created message to the store."""
         self.messages.append(message)
 
     async def aadd_messages(self, messages: Sequence[BaseMessage]) -> None:
-        """Add messages to the store"""
+        """Async add messages to the store"""
         self.add_messages(messages)
 
     def clear(self) -> None:
+        """Clear all messages from the store."""
         self.messages = []
 
     async def aclear(self) -> None:
+        """Async clear all messages from the store."""
         self.clear()

libs/core/langchain_core/chat_loaders.py

@@ -9,8 +9,16 @@ class BaseChatLoader(ABC):
 
     @abstractmethod
     def lazy_load(self) -> Iterator[ChatSession]:
-        """Lazy load the chat sessions."""
+        """Lazy load the chat sessions.
+
+        Returns:
+            An iterator of chat sessions.
+        """
 
     def load(self) -> List[ChatSession]:
-        """Eagerly load the chat sessions into memory."""
+        """Eagerly load the chat sessions into memory.
+
+        Returns:
+            A list of chat sessions.
+        """
         return list(self.lazy_load())

libs/core/langchain_core/chat_sessions.py

@@ -1,6 +1,5 @@
-"""**Chat Sessions** are a collection of messages and function calls.
+"""**Chat Sessions** are a collection of messages and function calls."""
 
-"""
 from typing import Sequence, TypedDict
 
 from langchain_core.messages import BaseMessage
@@ -11,6 +10,6 @@ class ChatSession(TypedDict, total=False):
     conversation, channel, or other group of messages."""
 
     messages: Sequence[BaseMessage]
-    """The LangChain chat messages loaded from the source."""
+    """A sequence of the LangChain chat messages loaded from the source."""
     functions: Sequence[dict]
-    """The function calling specs for the messages."""
+    """A sequence of the function calling specs for the messages."""