Constants fix

Hi Zeh!  I have some incoming pull-requests for you.  But first off thanks for writing this library, it's great!  Also, let me know if I'm doing something wrong, this is my first pull-request :-)

I saw your comments in the code about constants here, so I cleaned up the constant usage in the file.  The only downside here is the constants are public now, but I don't think that's that big a drawback.