Code hygiene.

src/key.rs

@@ -6,11 +6,10 @@
 //! Splines constructed with this crate have the property that it’s possible to change the
 //! interpolation mode on a key-based way, allowing you to implement and encode complex curves.
 
+use crate::interpolation::Interpolation;
 #[cfg(feature = "serialization")]
 use serde_derive::{Deserialize, Serialize};
 
-use crate::interpolation::Interpolation;
-
 /// A spline control point.
 ///
 /// This type associates a value at a given interpolation parameter value. It also contains an