# Sets the next bytes at position `pos` to the value of `c`, encoded in UTF-8
	#
	# Very unsafe, make sure to have room for this char prior to calling this function.
	private fun set_char_at(pos: Int, c: Char) do
		var cp = c.code_point
		if cp < 128 then
			self[pos] = cp
			return
		end
		var ln = c.u8char_len
		if ln == 2 then
			self[pos] = 0xC0 | ((cp & 0x7C0) >> 6)
			self[pos + 1] = 0x80 | (cp & 0x3F)
		else if ln == 3 then
			self[pos] = 0xE0 | ((cp & 0xF000) >> 12)
			self[pos + 1] = 0x80 | ((cp & 0xFC0) >> 6)
			self[pos + 2] = 0x80 | (cp & 0x3F)
		else if ln == 4 then
			self[pos] = 0xF0 | ((cp & 0x1C0000) >> 18)
			self[pos + 1] = 0x80 | ((cp & 0x3F000) >> 12)
			self[pos + 2] = 0x80 | ((cp & 0xFC0) >> 6)
			self[pos + 3] = 0x80 | (cp & 0x3F)
		end
	end