# Returns `self` escaped to UTF-16
	#
	# i.e. Represents `self`.`code_point` using UTF-16 codets escaped
	# with a `\u`
	#
	# ~~~
	# assert 'A'.escape_to_utf16 == "\\u0041"
	# assert 'è'.escape_to_utf16 == "\\u00e8"
	# assert 'あ'.escape_to_utf16 == "\\u3042"
	# assert '𐏓'.escape_to_utf16 == "\\ud800\\udfd3"
	# ~~~
	fun escape_to_utf16: String do
		var cp = code_point
		var buf: Buffer
		if cp < 0xD800 or (cp >= 0xE000 and cp <= 0xFFFF) then
			buf = new Buffer.with_cap(6)
			buf.append("\\u0000")
			var hx = cp.to_hex
			var outid = 5
			for i in hx.chars.reverse_iterator do
				buf[outid] = i
				outid -= 1
			end
		else
			buf = new Buffer.with_cap(12)
			buf.append("\\u0000\\u0000")
			var lo = (((cp - 0x10000) & 0x3FF) + 0xDC00).to_hex
			var hi = ((((cp - 0x10000) & 0xFFC00) >> 10) + 0xD800).to_hex
			var out = 2
			for i in hi do
				buf[out] = i
				out += 1
			end
			out = 8
			for i in lo do
				buf[out] = i
				out += 1
			end
		end
		return buf.to_s
	end