Function S2RegionCoverer.Options.levelMod
If specified, then only cells where (level - min_level) is a multiple of "level_mod" will be used (default 1). This effectively allows the branching factor of the S2CellId hierarchy to be increased. Currently the only parameter values allowed are 1, 2, or 3, corresponding to branching factors of 4, 16, and 64 respectively.
int levelMod() const;
Default
1