def bounds(self):
        """
        :return: List of tuples of all bounds on parameters.
        """
        bounds = []
        for p in self.params:
            if p.fixed:
                if p.value >= 0.0:
                    bounds.append([np.nextafter(p.value, 0), p.value])
                else:
                    bounds.append([p.value, np.nextafter(p.value, 0)])
            else:
                bounds.append([p.min, p.max])
        return bounds
:return: List of tuples of all bounds on parameters.