Standard Firmatta On GitHub Flowchart?

Hi I know what Standard Firmatta is and how it works, but can someone go through the link I posted and go step by step through the code to tell me how it works? Or better yet make a flowchart? Cause I am using it alot yet I have no idea how the code is doing what its doing? Whichever is easier, here is link:

https://github.com/firmata/arduino/blob/master/examples/StandardFirmata/StandardFirmata.ino