Like FromMinMax() except that the union covers the range of leaf cells
from "begin" (inclusive) to "end" (exclusive), as with Python ranges or
STL iterator ranges. If (begin == end) the result is empty.
REQUIRES: begin.is_leaf(), end.is_leaf(), begin <= end.
Like FromMinMax() except that the union covers the range of leaf cells from "begin" (inclusive) to "end" (exclusive), as with Python ranges or STL iterator ranges. If (begin == end) the result is empty.
REQUIRES: begin.is_leaf(), end.is_leaf(), begin <= end.