obj.use = require('reuse')
// mix some properties
obj.use({
  root: 'public'
})
// or
function root (that, dir) {
  that.root = dir
}
obj.use(root, 'public')
// in both cases
obj.should.have.property('root').equal('public')

function Klass () {
  this.a = 'a'
}
Klass.prototype.foo = 'foo'
obj.use(Klass)
obj.should.have.property('foo').equal('foo')
obj.should.not.have.property('a')