'The plot interval for the default geometric plot of the curve.
Parameters
parameter : str or Symbol, optional
Default value is \'t\';
otherwise the provided symbol is used.
Returns
plot_interval : list (plot interval)
[parameter, lower_bound, upper_bound]
See Also
limits : Returns limits of the parameter interval
Examples
>>> from sympy import Curve, sin
>>> from sympy.abc import x, t, s
>>> Curve((x, sin(x)), (x, 1, 2)).plot_interval()
[t, 1, 2]
>>> Curve((x, sin(x)), (x, 1, 2)).plot_interval(s)
[s, 1, 2]'

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

    t = _symbol(parameter, self.parameter)
    return ([t] + list(self.limits[1:]))
