Summary  
This chapter shows how to define a controller function and invoke a sequence of object methods to perform tasks, illustrating basic function definition and imperative commands in Python.  

General domain of usage  
Game development (controlling an in-game character)

## Welcome to the Python Ninja!

In this course, you will learn the **Python** programming language by playing a **game**. Instead of writing abstract code, you will control a **Ninja** inside a small world.

At the beginning, you will start with very simple commands: moving the Ninja around the map, picking up sushi, and placing them in the right spots.

As you progress, the challenges will slowly introduce core programming concepts: **functions** to reuse actions, **loops** to repeat steps, and **conditions** to make decisions.

### How to Control the Ninja?

The game provides you with commands that let you control the Ninja. Here is a simple code example to help you understand:

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Feel free to click **Run Code** to see how the code works.

Every time the level starts, the game looks for this block:
```
def ninja_controller(ninja):
```
Think of it as the place where you write all the **commands** for your Ninja. Everything written inside this block is executed from top to bottom:

- `ninja.go_up()` moves the Ninja one tile up on the map;
- `ninja.pick_sushi()` picks up the sushi on the tile where the Ninja is standing.

All Ninja commands must be indented inside `ninja_controller`.

For example, the code below **does not** work:
```
def ninja_controller(ninja):
    ninja.go_up()
ninja.pick_sushi()
```

Note

Welcome to the Python Ninja Course! This engaging and interactive course is designed to introduce you to the fundamentals of Python programming through a fun and educational game. You will guide a Ninja through various challenges, using Python to control movements and interact with objects like sushi. Starting with the basics, you will learn how to navigate the map, pick up and place sushi, and gradually progress to more complex programming concepts such as functions, loops, and conditional statements. Each chapter offers hands-on practice to reinforce your learning, culminating in exciting challenges that test your skills. Whether you are a complete beginner or looking to sharpen your coding abilities, this course provides a comprehensive and enjoyable learning experience. Join us and become a coding Ninja!

In the "Basic Controls" section, you will be introduced to the foundational features of Python through the engaging Ninja Game. You'll learn how to use Python commands to control your Ninja's movements and interactions on the grid, mastering essential functions like moving, picking up, and placing sushi. Through hands-on practice, you'll apply these skills to solve fun challenges, reinforcing your understanding of Python's basic capabilities.

In the "Advanced Controls" section, you will build on the skills you learned earlier and gain more control over the Ninja's movement. You'll learn how to navigate longer paths, handle turns and obstacles, and combine multiple actions into more efficient movement patterns. Through practice, you will develop better control logic and start thinking ahead, preparing you for more complex challenges later in the game.

In the "Functions" section, you will delve into the powerful Python feature of creating and utilizing functions to streamline your code. You will learn how to write functions to perform specific tasks, enhancing code reusability and clarity. By practicing decomposition, you will break down complex problems into simpler functions, mastering the art of organized and efficient coding.

In the "Loops" section, you will explore the essential Python feature of loops, which allows you to execute repetitive tasks efficiently. You will learn to implement both for loops and while loops, gaining the ability to automate actions and iterate over sequences. By mastering nested loops, you will tackle more complex scenarios, enhancing your ability to write concise and powerful code.

In the "If-Else Statements" section, you will learn how to use Python's conditional logic to make decisions within your code. You will explore how if-else statements allow your ninja to respond dynamically to different scenarios, enabling more intelligent and adaptable behavior. Through practical exercises, you will apply these concepts to solve challenges, enhancing your ability to write responsive and decision-driven code.

In the "Lists" section, you will learn how lists enable you to store multiple items, perform operations, and manage data efficiently. Through practical exercises, you will apply these concepts to solve challenges, improving your ability to write organized and dynamic code for handling collections of information.

In the "Challenges" section, you will apply your Python skills to tackle a series of engaging and complex problems. These challenges will test your understanding of loops, functions, and conditional logic as you guide your ninja to align columns, build letters, and traverse intricate patterns. By solving these puzzles, you will refine your coding abilities and gain confidence in applying Python to creative and real-world scenarios.

Getting Started

Welcome to the Python Ninja!

How to Control the Ninja?