  We provide a short proof of the quantisation of the Hall conductance for
gapped interacting quantum lattice systems on the two-dimensional torus. This
is not new and should be seen as an adaptation of the proof of [1], simplified
by making the stronger assumption that the Hamiltonian remains gapped when
threading the torus with fluxes. We argue why this assumption is very
plausible. The conductance is given by Berry's curvature and our key auxiliary
result is that the curvature is asymptotically constant across the torus of
fluxes.
