core[patch]: Fix doc-strings for code blocks (#23232)

Code blocks need extra space around them to be rendered properly by
sphinx

libs/core/langchain_core/runnables/base.py

@@ -1357,6 +1357,7 @@ class Runnable(Generic[Input, Output], ABC):
         Example:
 
         .. code-block:: python
+
             from langchain_core.runnables import RunnableLambda
             import time
 
@@ -3388,6 +3389,7 @@ class RunnableGenerator(Runnable[Input, Output]):
 
     RunnableGenerator makes it easy to implement custom behavior within a streaming
     context. Below we show an example:
+
         .. code-block:: python
 
             from langchain_core.prompts import ChatPromptTemplate
@@ -4384,12 +4386,15 @@ class RunnableEach(RunnableEachBase[Input, Output]):
             Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
         ] = None,
     ) -> RunnableEach[Input, Output]:
-        """
+        """Bind lifecycle listeners to a Runnable, returning a new Runnable.
-        Bind lifecycle listeners to a Runnable, returning a new Runnable.
 
-        on_start: Called before the runnable starts running, with the Run object.
+        Args:
-        on_end: Called after the runnable finishes running, with the Run object.
+            on_start: Called before the runnable starts running, with the Run object.
-        on_error: Called if the runnable throws an error, with the Run object.
+            on_end: Called after the runnable finishes running, with the Run object.
+            on_error: Called if the runnable throws an error, with the Run object.
+
+        Returns:
+            A new Runnable with the listeners bound.
 
         The Run object contains information about the run, including its id,
         type, input, output, error, start_time, end_time, and any tags or metadata
@@ -4408,15 +4413,18 @@ class RunnableEach(RunnableEachBase[Input, Output]):
         on_end: Optional[AsyncListener] = None,
         on_error: Optional[AsyncListener] = None,
     ) -> RunnableEach[Input, Output]:
-        """
+        """Bind async lifecycle listeners to a Runnable, returning a new Runnable.
-        Bind async lifecycle listeners to a Runnable, returning a new Runnable.
+
-
+        Args:
-        on_start: Called asynchronously before the runnable starts running,
+            on_start: Called asynchronously before the runnable starts running,
-                  with the Run object.
+                      with the Run object.
-        on_end: Called asynchronously after the runnable finishes running,
+            on_end: Called asynchronously after the runnable finishes running,
-                with the Run object.
+                    with the Run object.
-        on_error: Called asynchronously if the runnable throws an error,
+            on_error: Called asynchronously if the runnable throws an error,
-                with the Run object.
+                    with the Run object.
+
+        Returns:
+            A new Runnable with the listeners bound.
 
         The Run object contains information about the run, including its id,
         type, input, output, error, start_time, end_time, and any tags or metadata