code: func (c *Context) Next() {
  	c.index++
  	for c.index < int8(len(c.handlers)) {
  		c.handlers[c.index](c)
  		c.index++
  	}
  }
docs: /************************************/
  /*********** FLOW CONTROL ***********/
  /************************************/
  // Next should be used only inside middleware.
  // It executes the pending handlers in the chain inside the calling handler.
  // See example in GitHub.