# Set the value of a specific attribute.
	#
	# Parameters:
	#
	# * `index`: index of the attribute (zero-based).
	# * `value`: attribute's value.
	fun value_of=(index: Int, value: String) do
		assert index_in_bounds: index >= 0 and index < length
		data[index * 5 + 4] = value
	end