# Return a stack trace. One line per function
	fun stack_trace: String
	do
		var b = new FlatBuffer
		b.append(",---- Stack trace -- - -  -\n")
		for f in frames do
			b.append("| {f.mpropdef} ({f.current_node.location})\n")
		end
		b.append("`------------------- - -  -")
		return b.to_s
	end