Getting when trying to evolve the system.

[hellmersjl3ds]

When trying to evolve the code:
mesolve(h_t, psi0, taulist, [], process_rho, args)

I get the following error. It looks like it is expecting parameters to be passed in, but I'm not sure which ones to use.
`TypeError Traceback (most recent call last)
in ()
1 # Evolve the system, request the solver to call process_rho at each time step.
2
----> 3 mesolve(h_t, psi0, taulist, [], process_rho, args)

/home/jhellmers/anaconda3/lib/python3.6/site-packages/qutip/mesolve.py in mesolve(H, rho0, tlist, c_ops, e_ops, args, options, progress_bar, _safe_mode)
224
225 if _safe_mode:
--> 226 _solver_safety_check(H, rho0, c_ops, e_ops, args)
227
228 if progress_bar is None:

/home/jhellmers/anaconda3/lib/python3.6/site-packages/qutip/solver.py in _solver_safety_check(H, state, c_ops, e_ops, args)
834 _structure_check(Hdims, Htype, _temp_state)
835
--> 836 for ii in range(len(e_ops)):
837 if isinstance(e_ops[ii], Qobj):
838 _temp_state = e_ops[ii]

TypeError: object of type 'function' has no len()`