Code a filtering function wrapper in the prepare submodule

Issue

Currently, the filtering function for the catalog needs to be defined in the notebook. This is because the global parameters are not shared between modules and that the filtering function cannot receive more arguments.

What to do

I want to code a filtering function wrapper, let's call it filter_catalog that retrieves the global filtering parameters from the notebook and set them as global within the prepare script.

This would allow for the removing of the filtering function from the notebook.