calling external function with arguments

[Wimpy_Wellington]

I am new to python...

I am trying to call a function defined in a separate program, but I cannot figure out how to pass an argument. How to do?

The function I want to call is in this program:
testren.py:

import sys, getopt
global old_name
def renameit(argv):
   global old_name
   old_name = ''
   opts, args = getopt.getopt(argv,"ho:",["oldname="])
   for opt, arg in opts:
      if opt in ("-o", "--old_name"):
         old_name = arg  
   print ('in testren after - old_name =', old_name )

if __name__ == "__main__":
   print ('sys.argv ', sys.argv[1:])
   renameit(sys.argv[1:])

If I call testren.py directly, I get the desired results:

Output:
C:\python>python testren.py -o "my1.mp3"
sys.argv  ['-o', 'my1.mp3']
in testren after - old_name = my1.mp3

If I call it from another python program the arguments are not found, I cannot figure out how to pass the arguments. How to do?

calltestren.py:

import testren
if __name__ == '__main__':
    renargs = '-o "my1.mp3"'
    print('calling rename', renargs)
    testren.renameit(renargs)
    print('old_name<', old_name, '>')

I just get blanks where I expect a file name to be:

Output:
C:\python>python calltestren.py
calling rename -o "my1.mp3"
in testren after - old_name =
old_name<  >