Equivalent to bool(x) in Python, or not not x.
py_bool(x)An R scalar logical: TRUE or FALSE. If x is a
null pointer or Python is not initialized, FALSE is returned.
If the Python object defines a __bool__ method, then that is invoked.
Otherwise, if the object defines a __len__ method, then TRUE is
returned if the length is nonzero. If neither __len__ nor __bool__
are defined, then the Python object is considered TRUE.