If in one library: LIB, one API returns str
or a variable is of str, consider firstly port a n_LIB
that is only in pure Nim (NimPylib-independent) if possible.
For example, n_time for time, in which string shall be used.
Then let LIB import n_LIB and wrap around string to only return PyStr.
So does for seq <-> PyList.
In such a way, n_LIB is for Nim and LIB is for NimPylib.