You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: percentiles.rs
    path of file: ./repos/criterion.rs/src/stats/univariate
    
    the code of the file until where you have to start completion: use crate::stats::float::Float;
use cast::{self, usize};

/// A "view" into the percentiles of a sample
pub struct Percentiles<A>(Box
    
    unsafe fn at_unchecked(&self, p: A) -> A {
        let _100 = A::cast(100);
        debug_assert!(p >= A::cast(0) && p <= _100);
        debug_assert!(self.0.len() > 0);
        let len = self.0.len() - 1;

        if p == _100 {
            self.0[len]
        } else {
            let rank = (p / _100) * A::cast(len);
            let integer = rank.floor();
            let fraction = rank - integer;
            let n = usize(integer).unwrap();
            let &floor = self.0.get_unchecked(n);
            let &ceiling = self.0.get_unchecked(n + 1);

            floor + (ceiling - floor) * fraction
        }
    }