Help Getting the Tonry model of Peculiar velocity field running in python

I am attempting to translate the model of peculiar velocity flow given by Tonry et al (1999) from fortran into python, the language we use on my course, however I am experiencing difficulties in getting the thing to run.


I have attached the original fortran (sbf2flow) and my attempt at translating it into python (tonrymodel).

Any pointers or corrections would be greatly appreciated as this is not a computing project although I am not able to proceed until I have got this model working properly

 

i am getting the message 'return' outside function and I have played around but cant seem to shift that message.

 

so i got somewhere however now in line 123,
ivrw = int((vx*x + vy*y + vz*z) / math.sqrt(x*x+y*y+z*z))
it is telling me x is not defined, however im sure it is defined above