# Write an array header for `len` items in the shortest possible MessagePack _array_ format
	#
	# After writing the header, clients should write the array items.
	#
	# Require: `len <= 0xFFFF_FFFF`
	fun write_msgpack_array(len: Int)
	do
		if len <= 0x0F then
			write_msgpack_fixarray len
		else if len <= 0xFFFF then
			write_msgpack_array16 len
		else if len <= 0xFFFF_FFFF then
			write_msgpack_array32 len
		else
			abort
		end
	end