https://docs.vapi.ai/prompting-guide here have this text of the image. a guide on how to use external tools and APIs in the prompt. in the example it says: "If the user wants to know about something, use the get_data function with the parameter 'query', which will contain the user's question to initiate the process." my question is how to create this integration/get_data function (knowing that I have an API, that given a query it returns N documents)