operator < method
< operator to compare this and other
. Overriding it is optional,
it has a default implementation that uses == and > operators
USE EasyComparable IF YOU ONLY WANT TO COMPARE TO ANY Object
If you need to specify what Type is used on > and < operators, use SpecificComparable
Implementation
@override
bool operator <(covariant U other) => this != other && !(this > other);