Constructs a cell union from a vector of sorted, non-overlapping
S2CellIds. Unlike the other constructors, FromVerbatim does not require
that groups of 4 child cells have been replaced by their parent cell. In
other words, "cell_ids" must satisfy the requirements of IsValid() but
not necessarily IsNormalized().
Note that if the cell union is not normalized, certain operations may
return different results (e.g., Contains(S2CellUnion)).
REQUIRES: "cell_ids" satisfies the requirements of IsValid().
Constructs a cell union from a vector of sorted, non-overlapping S2CellIds. Unlike the other constructors, FromVerbatim does not require that groups of 4 child cells have been replaced by their parent cell. In other words, "cell_ids" must satisfy the requirements of IsValid() but not necessarily IsNormalized().
Note that if the cell union is not normalized, certain operations may return different results (e.g., Contains(S2CellUnion)).
REQUIRES: "cell_ids" satisfies the requirements of IsValid().