// Asserting APIs:
// - generated by Traceur (based on type annotations)
// - can be also used in tests for instance
assert.type(something, Type);
assert.returnType(returnValue, Type);
assert.argumentTypes(firstArg, Type, secondArg, Type);

// this can be used anywhere in the code
// (useful inside test, when we don't wanna define an interface)
assert(value).is(...)


// Custom type assert:
// - i have a custom type
// - adding an assert methos
assert.define(MyUser, function(value) {
  assert(value).is(Type, Type2); // or
  assert(value, 'name').is(assert.string);
  assert(value, 'contact').is(assert.structure({
    email: assert.string,
    cell: assert.string
  }));
  assert(value, 'contacts').is(assert.arrayOf(assert.structure({email: assert.string})));
});



// Define interface (an empty type with assert method)
// - returns an empty class with assert method
var Email = assert.define('IEmail', function(value) {
  assert(value).is(String);

  if (value.indexOf('@') !== -1) {
    assert.fail('has to contain "@"');
  }
});


// Predefined types
assert.string
assert.number
assert.boolean
assert.arrayOf(...types)
assert.structure(object)