# Read `self` until `nend` and append it to the `out` buffer.
	# Escape markdown special chars.
	private fun read_until(out: FlatBuffer, start: Int, nend: Char...): Int do
		var pos = start
		while pos < length do
			var c = self[pos]
			if c == '\\' and pos + 1 < length then
				pos = escape(out, self[pos + 1], pos)
			else
				for n in nend do if c == n then break label
				out.add c
			end
			pos += 1
		end label
		if pos == length then return -1
		return pos
	end