OpenAI Cookbook
OpenAI has some really cool Cookbooks - essentially, these are detailed examples of using the OpenAI API. Not just documentation, but rather a task-thought-implementation-explanation format. For instance, using Wikipedia data, the fine-tuning and embeddings approach is described in detail, showing the implementation of the same task in two different ways, highlighting the pros and cons of each approach and when to use which.
Returning to Function Calling, a detailed description and usage example is available at the link https://github.com/openai/openai-cookbook/blob/main/examples/How_to_call_functions_with_chat_models.ipynb
Other cookbooks are available here: https://github.com/openai/openai-cookbook
If you are writing your own programs, the cookbook is a great starting point that speeds up development. For the really lazy, you can feed GPT-4 a text description of your task and the text from the cookbook and get a ready-made solution.
P.S. LangChain has already supported Function Calling https://github.com/hwchase17/langchain/blob/master/docs/modules/agents/tools/tools_as_openai_functions.ipynb
