[firedrake] Trying to print discrete divergence

Dear all, I'm trying to assert that my projection in my incompressible case leaves my initial velocity to be discrete divergence free. I've tried print an L2 norm but must be writing it wrong as it causes causes the compiler to break. The relevant lines solve(DIVU_perp == DIVU, u_perp, solver_parameters={'ksp_rtol': 1e-14, 'pc_type' : 'none', 'ksp_type': 'lsqr'} ) u0 += u_perp # Print statement to verify initial velocity is divergence free u_div = assemble( div_u( u0 , dFdPproject ) ) u_div_norm = norm (u_div, norm_type="L2") print "l2 norm of discrete divergence on initial velocity is " % u_div_norm How would I go about getting the script to print that the velocity is verified as divergence free? Regards, Will