Adding variables to the model
The next step adds a matrix variable to the model:
# Create variables
x = m.addMVar(shape=3, vtype=GRB.BINARY, name="x")
A matrix variable is added through the addMVar() method on a
model object. In this case the matrix variable consists of a 1-D
array of 3 binary variables. Variables are always associated with a
particular model.
