things that are broken that should work::

A.<x> = AffineSpace(QQ, 1)
f1 = DynamicalSystem(x^2 + 1, A)
d = DynamicalSemigroup((f1))
one = QQ(1)
d.nth_iterate(1, one) #broken, use ZZ(n) to check if the input is an integer

d^one #broken



line ; issue

655 ; add a :: to separate the two examples
1009 ; add another example dehomogenizing at something other than 0
1028 ; change the error message to show new_system instead of ds. the user should see the dehomogenization
1133 ; add a test where the homogenization is not a dynamical system
1139 ; same issue as line 1028