contracts

Work in process.

Based on design by contract.

Motivation :

var f = function(a, b) {
	return a + b;
}

var f = f.pre(function(a, b) {
	a.should.be.a("number").and.above(0);
	b.should.be.a("number").and.above(0);
}).post(function(ret, a, b) {
	ret.should.be.equal(a + b);
});