I defined a QAHE hamiltonian: ham = ("alpha * (k_x * sigma_x - k_y * sigma_y)" "+ (m + beta * kk) * sigma_z" "+ (gamma * kk + U) * sigma_0") subs = {"kk": "k_x**2 + k_y**2"} Upon using the continuum.discretize I was able to plot bands etc but am struggling to plot the conductance. Using the method from the kwant documentation I am getting the following error: UserCodeError: Error occurred in user-supplied value function "onsite". See the upper part of the above backtrace for more information. I am new to kwant so any help would be appreciated!