Add an example

[mleonhard]

How about adding an example of how to use the equality checker classes?

final bool contentsEqual = (const ListEquality<Type>()).equals(list1, list2);

@override
bool operator ==(Object other) =>
  (other is MyClass) &&
  foo == other.foo &&
  (const ListEquality<Bar>()).equals(bars, other.bars);

[WalterLievens]

I really had to come to this page to understand how to use this function...

[sgehrman]

Still lacks a decent example in 2021

[jpSimkins]

Still trying to figure out how to use this package. Cannot seem to get it to work, even with the example above and looking at the tests. 2 matching lists are shown as not matching... Time to just do it manually