'The plot interval for the default geometric plot of the Ellipse.
Parameters
parameter : str, optional
Default value is \'t\'.
Returns
plot_interval : list
[parameter, lower_bound, upper_bound]
Examples
>>> from sympy import Point, Ellipse
>>> e1 = Ellipse(Point(0, 0), 3, 2)
>>> e1.plot_interval()
[t, -pi, pi]'

def plot_interval(self, parameter='t'):

    t = _symbol(parameter)
    return [t, (- S.Pi), S.Pi]
