Python code to express a large integer in words?

[ptah]

For interest I have included code below from the as400network Club Tech
iSeries Programming Tips - 06.21.01 it is written in IBM RPG IV and is a
kind of DLL (we call them service programs) that does the above, I would
like to see how much more succinct a Python equivalent could be, purely
because I would like to jump ship and code in something more expressive
and need to put the case for Python to people who are not in the habit
of thinking in an abstract way ;)

Any help greatly appreciated (I can't offer money, sorry).
Regards

Peter Moore
MJS400 (UK) Ltd

     H NoMain
      *  -------------------------------------------------------------
      *  -  Procedure prototypes                                     -
      *  -------------------------------------------------------------
     D CvtNbrToWords   PR           200
     D                               15  0 Value
      *  -------------------------------------------------------------
      *  -  Global variables                                         -
      *  -------------------------------------------------------------
     D MaxGrps         C                   5
     D Words           S             13    Dim( 99 )
     D                                     CtData
     D Grps            S              8    Dim( MaxGrps )
     D                                     CtData
      *  =============================================================
      *  =  Procedure:   CvtNbrToWords                               =
      *  =  Description: Convert number to words                     =
      *  =============================================================
     P CvtNbrToWords   B                   Export
      *  -------------------------------------------------------------
      *  -  Procedure interface                                      -
      *  -------------------------------------------------------------
     D CvtNbrToWords   PI           200
     D  Nbr                          15  0 Value
      *  -------------------------------------------------------------
      *  -  Variable declarations                                    -
      *  -------------------------------------------------------------
     D AlphaNbr        S             15
     D WorkFld         DS
     D  Work3                         3
     D  Work2                         2    Overlay( Work3 : 2 )
     D  Work1                         1    Overlay( Work3 : 1 )
     D Count           S              5I 0
     D Pos             S              5I 0
     D Idx             S              5I 0
     D RtnWords        S            200    Inz( *Blank )
      *  -------------------------------------------------------------
      *  -  Convert number to words                                  -
      *  -------------------------------------------------------------
     C                   Select

     C                   When      Nbr = *Zero
     C                   Eval      RtnWords = 'zero'

     C                   Other
     C                   If        Nbr < *Zero
     C                   Eval      RtnWords = 'negative'
     C                   Eval      Nbr = Nbr * -1
     C                   EndIf

     C                   Move      Nbr           AlphaNbr

     C                   Do        MaxGrps       Count

     C                   Eval      Pos   = ( Count * 3 ) - 2
     C                   Eval      Work3 = %Subst( AlphaNbr :
     C                                             Pos      :
     C                                             3        )
     C                   If        Work3 <> '000'

     C                   If        Work1 <> '0'
     C                   Clear                   Idx
     C                   Move      Work1         Idx
     C                   Eval      RtnWords = %TrimR( RtnWords )     +
     C                                        ' '                    +
     C                                        %TrimR( Words( Idx ) ) +
     C                                        ' hundred'
     C                   EndIf

     C                   If        Work2 <> '00'
     C                   Clear                   Idx
     C                   Move      Work2         Idx
     C                   Eval      RtnWords = %TrimR( RtnWords )     +
     C                                        ' '                    +
     C                                        %TrimR( Words( Idx ) )
     C                   EndIf

     C                   Eval      RtnWords = %TrimR( RtnWords )    +
     C                                        ' '                   +
     C                                        %TrimR( Grps( Count ) )

     C                   EndIf

     C                   EndDo

     C                   EndSl

     C                   Eval      RtnWords = %Trim( RtnWords )

     C                   Return    RtnWords

     P CvtNbrToWords   E

** CtData Words
one
two
three
four
five
six
seven
eight
nine
ten
eleven
twelve
thirteen
fourteen
fifteen
sixteen
seventeen
eighteen
nineteen
twenty
twenty-one
**..SNIPPED..**
ninety-nine
** CtData Grps
trillion
billion
million
thousand