R: In lpSolveAPI, how do I change the objective function from minimization to maximization?

Question

library(lpSolveAPI)
my.lp <- make.lp(nrow = 3, ncol = 2)
set.column(my.lp, 1, c(1, 1, 2))
set.column(my.lp, 2, c(3, 1, 0))
set.objfn(my.lp, c(1, 0))
set.constr.type(m