# Write an array header for `len` items, max of 0x0F items
	#
	# After writing the header, clients should write the array items.
	#
	# Require: `len <= 0x0F`
	fun write_msgpack_fixarray(len: Int)
	do
		assert len <= 0x0F
		write_byte 0b1001_0000 | len
	end