[Kwant] discretize continuous Hamiltonians

[Khani Hosein]

Dear authors,
I want to discretize continuous Hamiltonians of Weyl semimetal (PRL
115,246603 (2015)) using Kwant, but we have sin(kz),sin(ky)...in the
Hamiltonian, so it always shows the error message. I have already imported
sin and cos from math. Could you give me any suggestion?
Hosein Khani