  In this article we show how to compute the chromatic quasisymmetric function
of indifference graphs from the modular law introduced by Guay-Paquet. We
provide an algorithm which works for any function that satisfies this law, such
as unicellular LLT polynomials. When the indifference graph has bipartite
complement it reduces to a planar network, in this case, we prove that the
coefficients of the chromatic quasisymmetric function in the elementary basis
are positive unimodal polynomials and characterize them as certain $q$-hit
numbers (up to a factor). Finally, we discuss the logarithmic concavity of the
coefficients of the chromatic quasisymmetric function.
