---
sidebar_label: Fake LLM
---

# Fake LLM

## Overview

This documentation provides an overview of the `fake` package, which offers a simulated implementation of a Language Learning Model (LLM) for testing purposes in Go applications.

## Installation

To use the `fake` package, import it into your Go project:

```bash
go get "github.com/tmc/langchaingo"
```



## Prerequisites
Ensure you have Go programming language installed on your machine (version 1.15 or higher recommended).

## Example Usage
Here is an example demonstrating how to use the fake package:


```go
package main

import (
	"context"
	"fmt"
	"log"

	"github.com/tmc/langchaingo/llms"
	"github.com/tmc/langchaingo/llms/fake"
)

func main() {
	// Creating a fake LLM with initial responses.
	responses := []string{
		"Hello!",
		"How are you?",
		"I'm fine, thanks.",
	}
	llm := fake.NewFakeLLM(responses)

	// Calling the fake LLM with a prompt.
	ctx := context.Background()
	response, err := llm.Call(ctx, "Hi there!")
	if err != nil {
		fmt.Printf("Error calling LLM: %v\n", err)
	} else {
		fmt.Println("LLM Response:", response)
	}

	// Adding a new response and testing again.
	llm.AddResponse("Goodbye!")
	response, err = llm.Call(ctx, "See you later!")
	if err != nil {
		fmt.Printf("Error calling LLM: %v\n", err)
	} else {
		fmt.Println("LLM Response:", response)
	}
}
```

# API Reference
`NewFakeLLM(responses []string) *LLM`

Creates a new instance of the fake LLM with the provided responses.

`LLM.Call(ctx context.Context, prompt string) (string, error)`

Simulates calling the model with a specific prompt and returns a fictional response.

`LLM.Reset()`

Resets the fake LLM, allowing responses to cycle through again.

`LLM.AddResponse(response string)`

Adds a new response to the list of possible responses of the fake LLM.

# Purpose

The fake package is designed to facilitate testing of applications that interact with language learning models, without relying on real model implementations. It helps validate application logic and behavior in a controlled environment.