[PyMOL] selection in python script

[<kk...@ga...>]

Dear pymolers,

I can select some residues in my protein in the command prompt
by saying for example
 select prot = (////VAL or ////PRO or ////GLY)
but now I have trouble translating this into python script.
I tried many varieties including something like
 cmd.select( prot, (////VAL or ////PRO or ////GLY) )
but by far nothing works.
I did not try to write .pml script because I thought that
I need to use python script so that I can do some
string and file processing (iterating through my pdb files).
Any suggestion?

Regards,
K.K.Liang