Problem:
Find the second order expansion about $x = -1$ of the composition $f(g(x))$ for $f(x) = \cos (x)$ and $g(x) = $\cosh (x)$
from sympy import *
from sympy.abc import x

f = cos(x)
g = cosh(x)
series = f.subs(x, g).series(x, -1, 2)
print(series)
