'Check a triangular()-like function.'

def _check_triangular(self, func2, func3, ptr):

    r = self._follow_cpython(ptr)
    if (func2 is not None):
        self._check_dist(func2, r.triangular, [(1.5, 3.5), ((-2.5), 1.5), (1.5, 1.5)])
    self._check_dist(func3, r.triangular, [(1.5, 3.5, 2.2)])
