Question About the Code of Provider

I am learning the code of CS 2.1 these days ,

but something make me confused ...... Providers

For Example ,

CSApplication.Instance().ExecutePrePostEvents(xxxxxxxxxx)

line 78 in CSEvents.cs

 

I want to see (and modify )what ExecutePrePostEvents Doing ?

and I found it hard to locate the code which defining ExecutePrePostEvents  ....
>____<

 

can somebody help ?