# Write `value` over 8 unsigned bytes, following 1 metadata byte
	#
	# Require: `value >= 0x00 and value <= 0xFFFF_FFFF_FFFF_FFFF`
	fun write_msgpack_uint64(value: Int)
	do
		write_byte 0xCF
		write_bytes value.to_bytes(n_bytes=8)
	end