fn reduce<F, T>(&self, init: T, f: F) -> f64
    where
        F: Fn(f64, f64) -> f64,
        T: Into<f64> + Copy,
    {
        self.iter().fold(init.into(), |x, &y| f(x, y))
    }
reduce for `Vec<f64>`

# Examples
```
#[macro_use]
extern crate peroxide;
use peroxide::fuga::*;

fn main() {
let a = seq!(1,100,1);
assert_eq!(a.reduce(0, |x,y| x + y), 5050f64);
}
```
src/structure/vector.rs