Looking at the function arg, seems you need to do something like
simus = pm.Deterministic('simus', run_simu({'theta1': theta1, 'theta2': theta2, 'theta3': theta3}))
Looking at the function arg, seems you need to do something like
simus = pm.Deterministic('simus', run_simu({'theta1': theta1, 'theta2': theta2, 'theta3': theta3}))