Add an SOS constraint to the model. Please refer to this section for details on SOS constraints.
type: SOS type (can be GRB.SOS_TYPE1 or GRB.SOS_TYPE2).
vars: List of variables that participate in the SOS constraint.
weights (optional): Weights for the variables in the SOS constraint. Default weights are 1, 2, ...
New SOS object.
model.addSOS(GRB.SOS_TYPE1, [x, y, z], [1, 2, 4])