solve ODE with sympy

[Sergey_Novak]

Hello
Is it possible to solve this differential equation using sympy?
z'' + c * z = -sign(z')
I tried to solve it and got the following error:

Error:
No algorithms are implemented to solve equation _Dummy_39 + x(t) + sign(_X0)

Code:

import sympy as sp
import numpy as np
sp.init_printing()


t = sp.symbols('t')
x = sp.Function('x')(t)
x_dot = x.diff(t)
x_two_dot = (x.diff(t)).diff(t)

expr = sp.Eq(x_two_dot, -sp.sign(x_dot) -x )

sol = sp.dsolve(expr); sol

Thanks for your helps