docs: function Unit(desc){
  	if (!(this instanceof Unit)) return new Unit(desc);
  
  	this.$unitAttached = true;
  	this.$unitHandlers = {};
  	this.$unitPrefix = '';
  	if (Unit.$prototyping) return this;
  	if (desc){
  		this.extendUnit(desc);
  		this.setupUnit();
  	}
  	return this;
  }