An ExpertSpec is a class instance convertable to and from a str.
The fields are
training_start: YYYYMM
training_stop: YYYYMM
x_transformation: one of {"none", "log1p"}
y_transformation: one of {"none", "log1p"}
model: one of {"rf", "en", "gb"}. For "en" models, the training data are always standardized by subtracting the mean and dividing by the standard deviation
hp1 .. hpN: the hyperparameters specific to the model
An ExpertSpec is a class instance convertable to and from a str.
The fields are