def _contains(self, other):
        if other.is_integer and other.is_nonnegative:
            return S.true
        elif other.is_integer is False or other.is_nonnegative <= False:
            return S.false
dataset/ETHPy150Open sympy/sympy/sympy/sets/fancysets.py/Naturals0._contains/operator `is` -> `<=`