def paths_to_deltas(points)
      [points].flatten.map { |p| p.tap { p[:path] = DELTA + p[:path] } }
    end
def paths_to_deltas(points)
      [points].flatten.map { |p| p.tap { p[:path] = DELTA + p[:path] } }
    end
Prefix all paths in a points array (as passed to
 #write_delta() with a delta symbol

 @param points [Array[Hash]] see #write()
 @return [Array[Hash]]