function encode(s)
	ch = nothing
	cnt = 1
	result = ""
	for c ∈ s
		if ch ≡ nothing
			ch = c
			continue
		end
		if ch == c
			cnt += 1
		else
			result *= cnt > 1 ? "$cnt$ch" : "$ch"
			ch = c
			cnt = 1
		end
	end
	if ch ≢ nothing
		result *= cnt > 1 ? "$cnt$ch" : "$ch"
	end
	result
end



function decode(s)
	items = collect(eachmatch(r"(\d+)?(.)", s))
	result = ""
	for item ∈ items
		cnt = parse(Int, (item[1] ≡ nothing) ? "1" : item[1]) 
		result *= item[2]^cnt
	end
	result
end