Minor fixes episode 3

        with conn.connect() as galaxy_connection:

            data_store = galaxy_connection.create_data_store(name="fractal_store")

            data_store.persist()

            print("Executing fractal tool. This might take a few minutes.")

            output = tool.run(data_store, params)

            output.get_dataset("output").download("image.png")

Let\'s create a `Fractal` class that uses `nova-galaxy` to run the `neutrons_fractal` tool on NDIP. You can find the complete code for this episode in the `code/episode_3` directory. 

**1. `Fractal` Class (`src/nova_tutorial/models/fractal.py`):**

**1. `Fractal` Class (`src/nova_tutorial/app/models/fractal.py`):**

To get started, let\'s create the Fractal class. Create a new file at `src/nova_tutorial/models/fractal.py`. Add the following pieces of code to the newly created file. 

To get started, let\'s create the Fractal class. Create an empty file at `src/nova_tutorial/app/models/fractal.py`. Add the following pieces of code to the newly created file. 

*   **Imports**:  The `Fractal Class` will start by importing the necessary classes from `nova-galaxy`:

    from nova.galaxy import Connection, Parameters, Tool

    ```

*   **`__init__` method**:  In the `__init__` method, we instantiate the `Fractal` class. Note how we retrieve `GALAXY_URL` and `GALAXY_API_KEY` from environment variables. This establishes how we will connect to NDIP:

*   **`__init__` method**:  In the `__init__` method, we initialize the `Fractal` class. Note how we retrieve `GALAXY_URL` and `GALAXY_API_KEY` from environment variables. This establishes how we will connect to NDIP:

    ```python

    class Fractal:

        with conn.connect() as galaxy_connection:

            data_store = galaxy_connection.create_data_store(name="fractal_store")

            data_store.persist()

            print("Executing fractal tool. This might take a few minutes.")

            output = tool.run(data_store, params)

            output.get_dataset("output").download("image.png")

        ```

**2. `main.py` - Calling the Model (`src/nova_tutorial/main.py`):**

**2. `main.py` - Calling the Model (`src/nova_tutorial/app/main.py`):**

We are now going to modify the existing `main.py` file. Change the main method to match the code below.