diff --git a/README.md b/README.md
index ed585b1..11e1a57 100644
--- a/README.md
+++ b/README.md
@@ -139,44 +139,6 @@ answer
 > :white_check_mark: **answer: It will still take 1 hour to dry 30 shirts under the sun,**
 > **assuming they are all laid out properly to receive equal sunlight.**
 
-### Updates:
-
-**29th Sept 2024**:
-
-We are introducing a new engine based on [litellm](https://github.com/BerriAI/litellm). This should allow
-you to use any model you like, as long as it is supported by litellm. This means that now
-**Bedrock, Together, Gemini and even more** are all supported by TextGrad!
-
-In addition to this, with the new engines it should be easy to enable and disable caching.  
-
-We are in the process of testing these new engines and deprecating the old engines. If you have any issues, please let us know!
-
-The new litellm engines can be loaded with the following code: 
-
-An example of loading a litellm engine:
-```python
-engine = get_engine("experimental:gpt-4o", cache=False)
-
-# this also works with
-
-set_backward_engine("experimental:gpt-4o", cache=False)
-```
-
-An example of forward pass:
-```python
-
-import httpx
-from textgrad.engine_experimental.litellm import LiteLLMEngine
-
-LiteLLMEngine("gpt-4o", cache=True).generate(content="hello, what's 3+4", system_prompt="you are an assistant")
-
-image_url = "https://upload.wikimedia.org/wikipedia/commons/a/a7/Camponotus_flavomarginatus_ant.jpg"
-image_data = httpx.get(image_url).content
-```
-
-In the examples folder you will find two new notebooks that show how to use the new engines.
-
-
 We have many more examples around how TextGrad can optimize all kinds of variables -- code, solutions to problems, molecules, prompts, and all that!
 
 ### Tutorials
diff --git a/tests/test_basics.py b/tests/test_basics.py
index dba4fa6..0f06b8c 100644
--- a/tests/test_basics.py
+++ b/tests/test_basics.py
@@ -68,6 +68,57 @@ def test_openai_engine():
     os.environ['OPENAI_API_KEY'] = "fake_key"
     engine = ChatOpenAI()
 
+
+def test_set_backward_engine():
+    from textgrad.config import set_backward_engine, SingletonBackwardEngine
+    from textgrad.engine.openai import ChatOpenAI
+    from textgrad.engine_experimental.litellm import LiteLLMEngine
+
+    engine = ChatOpenAI()
+    set_backward_engine(engine, override=False)
+    assert SingletonBackwardEngine().get_engine() == engine
+
+    new_engine = LiteLLMEngine(model_string="gpt-3.5-turbo-0613")
+    set_backward_engine(new_engine, True)
+    assert SingletonBackwardEngine().get_engine() == new_engine
+
+    with pytest.raises(Exception):
+        set_backward_engine(engine, False)
+
+def test_get_engine():
+    from textgrad.engine import get_engine
+    from textgrad.engine.openai import ChatOpenAI
+    from textgrad.engine_experimental.litellm import LiteLLMEngine
+
+    engine = get_engine("gpt-3.5-turbo-0613")
+    assert isinstance(engine, ChatOpenAI)
+
+    engine = get_engine("experimental:claude-3-opus-20240229")
+    assert isinstance(engine, LiteLLMEngine)
+
+    engine = get_engine("experimental:claude-3-opus-20240229", cache=True)
+    assert isinstance(engine, LiteLLMEngine)
+
+    engine = get_engine("experimental:claude-3-opus-20240229", cache=False)
+    assert isinstance(engine, LiteLLMEngine)
+
+    # get local diskcache
+    from diskcache import Cache
+    cache = Cache("./cache")
+
+    engine = get_engine("experimental:claude-3-opus-20240229", cache=cache)
+    assert isinstance(engine, LiteLLMEngine)
+
+    with pytest.raises(ValueError):
+        get_engine("invalid-engine")
+
+    with pytest.raises(ValueError):
+        get_engine("experimental:claude-3-opus-20240229", cache=[1,2,3])
+
+    with pytest.raises(ValueError):
+        get_engine("gpt-4o", cache=True)
+
+
 # Test importing main components from textgrad
 def test_import_main_components():
     from textgrad import Variable, TextualGradientDescent, EngineLM
diff --git a/textgrad/engine/__init__.py b/textgrad/engine/__init__.py
index ea7c6c1..2697faf 100644
--- a/textgrad/engine/__init__.py
+++ b/textgrad/engine/__init__.py
@@ -35,6 +35,9 @@ def get_engine(engine_name: str, **kwargs) -> EngineLM:
     if "seed" in kwargs and "gpt-4" not in engine_name and "gpt-3.5" not in engine_name and "gpt-35" not in engine_name:
         raise ValueError(f"Seed is currently supported only for OpenAI engines, not {engine_name}")
 
+    if "cache" in kwargs and "experimental" not in engine_name:
+        raise ValueError(f"Cache is currently supported only for LiteLLM engines, not {engine_name}")
+
     # check if engine_name starts with "experimental:"
     if engine_name.startswith("experimental:"):
         engine_name = engine_name.split("experimental:")[1]
diff --git a/textgrad/engine_experimental/litellm.py b/textgrad/engine_experimental/litellm.py
index 48b4c10..e28845c 100644
--- a/textgrad/engine_experimental/litellm.py
+++ b/textgrad/engine_experimental/litellm.py
@@ -25,7 +25,7 @@ def __init__(self,
                  model_string: str,
                  system_prompt: str = DEFAULT_SYSTEM_PROMPT,
                  is_multimodal: bool = True,
-                 cache=Union[dc.Cache, bool]):
+                 cache: Union[dc.Cache, bool] = False):
 
         super().__init__(
             model_string=model_string,