Thank you for your answers and their precision.
For you, the fact that IronPython doesn’t support CPython is not limiting ?
For example, I tried to use a SVN python package (PySvn) (to get Revision number of Revit files) inside Dynamo but it didn’t work. Maybe I did not do the right thing …
But it works outside Dynamo and i create a Excel File readable in Dynamo (there is allways a solution 
)
I have to progress understanding the IronPython implementation and the possibilities it offer… so, i’ll be back 
Great thanks.