'Check a exponential()-like function.'

def _check_exponential(self, func1, func0, ptr):

    r = self._follow_numpy(ptr)
    if (func1 is not None):
        self._check_dist(func1, r.exponential, [(0.5,), (1.0,), (1.5,)])
    if (func0 is not None):
        self._check_dist(func0, r.exponential, [()])
