mod test {
    use builder_pattern::Builder;

    // Public structure
    #[derive(Builder, Debug)]
    pub struct PublicTest {
        pub a: i32,
        pub b: Option<i32>,
        c: f64,
    }
}

use test::*;

pub fn main() {
    let t1 = PublicTest::new()
        .a(333)
        .b(Some(123))
        .c(1.234) // Cannot access `c` because it is private.
        .build();
    println!("{:?}", t1);
}