int_set <- c(2, 3, 5)
str_set <- c("one", "two", "three")
# Trap: c() with nothing is NULL, not a vector
not_set <- c()
# class(not_set) = NULL
cat("int_set =", int_set, "\n")
cat("str_set =", str_set, "\n")
cat("class(not_set) =", class(not_set), "\n")