fn fmap<F>(&self, f: F) -> Vec<f64>
    where
        F: Fn(f64) -> f64,
    {
        let mut v = self.clone();
        v.iter_mut().for_each(|x| *x = f(*x));
        v
    }
fmap for `Vec<f64>`

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

fn main() {
let a = c!(1,2,3,4,5);
assert_eq!(a.fmap(|x| x*2f64), seq!(2,10,2));
}
```
src/structure/vector.rs