langchain[patch], experimental[minor]: Adds OllamaFunctions wrapper (#13330)

CC @baskaryan @hwchase17 @jmorganca 

Having a bit of trouble importing `langchain_experimental` from a
notebook, will figure it out tomorrow

~Ah and also is blocked by #13226~

---------

Co-authored-by: Lance Martin <lance@langchain.dev>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/langchain/langchain/llms/ollama.py

@@ -94,11 +94,18 @@ class _OllamaCommon(BaseLanguageModel):
     template: Optional[str] = None
     """full prompt or prompt template (overrides what is defined in the Modelfile)"""
 
+    format: Optional[str] = None
+    """Specify the format of the output (e.g., json)"""
+
+    timeout: Optional[int] = None
+    """Timeout for the request stream"""
+
     @property
     def _default_params(self) -> Dict[str, Any]:
         """Get the default parameters for calling Ollama."""
         return {
             "model": self.model,
+            "format": self.format,
             "options": {
                 "mirostat": self.mirostat,
                 "mirostat_eta": self.mirostat_eta,
@@ -121,7 +128,7 @@ class _OllamaCommon(BaseLanguageModel):
     @property
     def _identifying_params(self) -> Mapping[str, Any]:
         """Get the identifying parameters."""
-        return {**{"model": self.model}, **self._default_params}
+        return {**{"model": self.model, "format": self.format}, **self._default_params}
 
     def _create_stream(
         self,
@@ -155,6 +162,7 @@ class _OllamaCommon(BaseLanguageModel):
             headers={"Content-Type": "application/json"},
             json={"prompt": prompt, **params},
             stream=True,
+            timeout=self.timeout,
         )
         response.encoding = "utf-8"
         if response.status_code != 200: