please help me to analysis the growParts function in the autopart.py

["Dawei Pang" <pangdae@xxxxxxxxx>]

Hi,there,
               I found there was an item "Fill all space up to(MB)"  in  the "Add Partition" dialog.I did not know what was the difference between that and "Fixed size" item. I got the growParts function in the anaconda code and found  that difficult to understand in a short time. Please give me some  explained  and analysis.
               Thank you very much.