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: cuboid.rs
    path of file: ./repos/parry/src/shape
    
    the code of the file until where you have to start completion: //! Support mapping based Cuboid shape.

use crate::math::{Point, Real, Vector};
#[cfg(feature = "dim3")]
use crate::shape::Segment;
use crate::sh
    
    pub fn feature_normal(&self, feature: FeatureId) -> Option<Unit<Vector<Real>>> {
        match feature {
            FeatureId::Face(id) => {
                let mut dir: Vector<Real> = na::zero();

                if id < 2 {
                    dir[id as usize] = 1.0;
                } else {
                    dir[id as usize - 2] = -1.0;
                }
                Some(Unit::new_unchecked(dir))
            }
            FeatureId::Vertex(id) => {
                let mut dir: Vector<Real> = na::zero();

                match id {
                    0b00 => {
                        dir[0] = 1.0;
                        dir[1] = 1.0;
                    }
                    0b01 => {
                        dir[1] = 1.0;
                        dir[0] = -1.0;
                    }
                    0b11 => {
                        dir[0] = -1.0;
                        dir[1] = -1.0;
                    }
                    0b10 => {
                        dir[1] = -1.0;
                        dir[0] = 1.0;
                    }
                    _ => return None,
                }

                Some(Unit::new_normalize(dir))
            }
            _ => None,
        }
    }