sage: from sympy import sympify
sage: integral(x, x, 0, 1, hold=True)
integrate(x, x, 0, 1)
sage: sympify(_)
...
ValueError: Invalid limits given: (x, 0, 1)
sage: integral(x, x, 0, 1, hold=True)._sympy_()
...
ValueError: Invalid limits given: (x, 0, 1)