In notebooks, you can define features inline using the syntax shown below.

Consider the following feature class definition for RocketEngine

notebook.ipynb
from chalk.features import features

@features
class RocketEngine:
    id: int
    mass: float
    volume: float
    thrust: float

If we wanted to define a feature inline in a notebook cell, we could do so using the underscore syntax below:

notebook.ipynb
RocketEngine.density: float = _.mass / _.volume