// output trait and some possibilities for outputs
pub trait Output {
    fn write(&mut self, data : &str);
}


pub struct DummyOutput {
    out : String
}


impl Output for DummyOutput {
    fn write(&mut self, data : &str) {
        self.out += data;
    }
}


impl DummyOutput {
    pub fn print(&mut self) {
        println!("{}", self.out);
    }

    pub fn spool(self) -> String {
        self.out
    }

    pub fn new() -> DummyOutput {
        DummyOutput {
            out : String::new()
        }
    }
}