# Gets the char index of byte at position `n` in a UTF-8 String
	#
	# `char_from` and `byte_from` are cached values to seek from.
	#
	# NOTE: char_from and byte_from are not guaranteed to be valid cache values
	# It it up to the client to ensure the validity of the information
	fun byte_to_char_index_cached(n, char_from, byte_from: Int): Int do
		var ns_i = byte_from
		var my_i = char_from

		while ns_i < n do
			ns_i += length_of_char_at(ns_i)
			my_i += 1
		end

		while ns_i > n do
			ns_i = find_beginning_of_char_at(ns_i - 1)
			my_i -= 1
		end

		return my_i
	end