This class is a wrapper around the formula class. It is not intended for
users to directly manipulate and create new objects.
raw_formula[formula] The raw formula call
translated_formula[formula] The translated formula call ready to be evaluated.
vars[list] List of relevant variables for the evaluation of the different smooths.
lag_varsSmooth lag variables used for predictions
response[charatcer] The response variable in the formula.
is_fitted[logical] Whether this formula has already been fitted.
See the mgcv function for defining smooths: s().