....: solid=True)
sage: A = random_matrix(QQ, K1.lattice_dim(), algorithm='unimodular')
sage: K2 = Cone( [ A*r for r in K1.rays() ], lattice=K1.lattice())
....: solid=True)
sage: A = random_matrix(QQ, K1.lattice_dim(), algorithm='unimodular')
sage: K2 = Cone( [ A*r for r in K1.rays() ], lattice=K1.lattice())