//! trait weighted set
//!//!/// A Trait to define association of a weight to an object.
/// Typically we could implement trait WeightedSet for any collection of Object if we have a function giving a weight to each object
/// Then hash_wset function can be used.
pubtraitWeightedSet{typeObject;/// returns the weight of an object
fnget_weight(&self, obj:&Self::Object)->f64;}