You can't get a NaN from a None value in Python. (Duck typing still has rules) The error you have posted isn't a Python error. Looking a bit deeper, the error

You can't get a NaN from a None value in Python. (Duck typing still has rules) The error you have posted isn't a Python error. Looking a bit deeper, the error occurs in C++ code. C++ is a statically typed language, last time I checked.