Use lys as Python interpreter

Use Python interpreter

After starting lys, you see the main window.

../_images/overview.png

Click “Show” button at the bottom-right edge to show the command log.

../_images/ShowButton.png

Type the command below in the text box at the bottom:
```
print("Hello, lys")
```

../_images/command.png

You see the “print” command is executed as Python command.

../_images/commandResult.png

It’s done! You can execute all Python commands from the Python interpreter in lys.

Define new function

Next, let’s try to define new function and execute. Press Ctrl+P to open proc.py file.

../_images/Proc.png

Define function below and Press Ctrl+S to save the contents:
```
def add(value):
    return value + 1
```

It is saved as “./module/proc.py”.

../_images/Function1.png

Type the code below to execute “add” function from the command line (You see “Result: 4”):
```
print("Result:", add(3))
```

../_images/AddFunc.png

It’s done! You can define arbitrary function and class in proc.py file. If you want to understand what is done for detail, see Understanding shell in lys

Now you can do everything that Python can do in lys. Go to next step(Display graphs in lys)