init from(root: Concat, pos: Int) do
		var r = new RopeCharIteratorPiece(root, false, true, null)
		var rnod: String = root
		var off = pos
		loop
			if rnod isa Concat then
				if off >= rnod._left.length then
					off -= rnod._left.length
					rnod = rnod._right
					r = new RopeCharIteratorPiece(rnod, false, true, r)
				else
					r.ldone = true
					rnod = rnod._left
					r = new RopeCharIteratorPiece(rnod, false, true, r)
				end
			else
				str = rnod.as(FlatString)
				r.ldone = true
				iter = r
				self.pos = pos - off
				break
			end
		end
	end