code: function three(context, next) {
    console.log('Hi from three', context);
    setTimeout(function() {
      context.three = 'Hello';
      console.log('Hello from three', context);
    }, 1000);
  }
docs: Function Three.
  Example function, logs 'hello' and currect context.
  
  @param {Object} context Current context object.
  @param {Function} next Next middleware in chain.