from sympy import symbols
from spb import plot
x = symbols('x')
p1 = plot(x**2, show=False)
p2 = plot(x, -x, show=False)
p1.extend(p2)
p1
# Expected:
## Plot object containing:
## [0]: cartesian line: x**2 for x over (-10.0, 10.0)
## [1]: cartesian line: x for x over (-10.0, 10.0)
## [2]: cartesian line: -x for x over (-10.0, 10.0)
p1.show()