调用它

• This method is called by the . net framework , this should not be called
  此方法由. net framework调用，但不应调用它。
• Instead , one writes a function that , when called , returns a generator
  相反，编写一个函数，当调用它时，返回生成器。
• Custom events allow the event to call its event handlers asynchronously
  自定义事件允许事件异步调用它的事件处理程序。
• Before using the instance returned by this constructor , you must invoke its
  使用此构造函数返回的实例之前，必须调用它的
• It is called like this
  可以这样调用它：
• Called when the schema of the data source for the associated control changes
  当关联控件的数据源架构更改时，将调用它。
• And call the appropriate
  并调用它相应的
• Method , it invokes it
  方法，则调用它。
• A function is a block of code that can be executed whenever we need it
  函数实际上是一个统一的代码块，你可以随时调用它。
• It is unbound , which means it can be called directly from any context
  它是未绑定的，也就是说可以直接从任何上下文调用它。