fix bug due to modularization

Author: dcoudert

src/sage/geometry/polyhedron/base_ZZ.py

@@ -414,6 +414,7 @@ def ehrhart_polynomial(self, engine=None, variable='t', verbose=False, dual=None
             t^6 + 6*t^5 + 15*t^4 + 20*t^3 + 15*t^2 + 6*t + 1
 
             sage: # optional - pynormaliz
+            sage: from itertools import product
             sage: def hypercube(d):
             ....:     return Polyhedron(vertices=list(product([0,1],repeat=d)),backend='normaliz')
             sage: hypercube(3).ehrhart_polynomial(engine='normaliz')