Suggestion: split this mesh into for disjoint meshes, one for fermions, one for bosons, each for specifying both positive and negative or only positive frequencies.
Andrey: [Q] There seem to be a number of conditionals - this is error-susceptible for future implementations.
The Matsubara mesh right now has two bools: negative/poisitve or only positive, and boson or fermion. Should we split these into two or four meshes?