Indentation and Dedentation

Hi, I want to make a grammar with Python-style indentation. In Python:

```py
def stuff():
    if True:
        if True:
            for i in range(2):
                print(i)
    print("YAY")
```

How would I make `INDENT` and `DEDENT` tokens using better-parse? I couldn't find any better-parse examples or tests showcasing how to do this.