Sometimes adding a parameter at the beginning or end of parameters list would make the resulting signature invalid. Typically, adding a keyword-only parameter before a keyword-or-positional, or adding a parameter without default after a parameter with a default (and conversely)...

Two new arguments first_possible and last_possible could allow the users to ask for a "smart insert first" and "smart insert last" feature.

This would help solving smarie/python-pytest-cases#279
in a reusable way.