Are there any methods to serialize a function that call function from other Python module file

Currently, I am developing a extension of the workflow system that going to send and submit the function to execute on clusters.

The `register_pickle_by_value` function is not going to work for me because I don't know which are user module files and which are on the Python path.

The problem is after serialize and send the serialize file to run on the remote server(It has NFS, but don't have the same absolute path and I need to run on the other directory) It cannot find the `ext` module.

Any suggestion?

Example
main.py
```
from ext import add

def compute( a, b ):
return add( a, b )
```

ext.py
```
def add( a, b ):
return a + b
```