Quantifiers
It's very common to work with collections (i.e. Arrays) so it should be easy to match against them.
ass(data).some.equal(10); // At least one equals 10
ass(data).all.lessThan(20); // All of them are < 20
ass(data).none.empty; // None of them is an empty value
All quantifiers support async expressions too, so you can for instance operate over a list of promises by using them.
ass([p1,p2,p3]).all.resolve.be.a.number.above(1000)
.catch(function (err) {
console.error(err)
})