def name_increment(net_name):
	"""
	produces a new net name by incrementing its sub id character
	e.g.:
		- FlowBot15313548 becomes FlowBot15313548/a
		- FlowBot15313548/a becomes FlowBot15313548/b
		- etc.
	:param net_name: the old name
	:return: the new name
	"""
	new_name = net_name.split("_")
	if len(new_name) == 1:
		new_name = new_name[0] + "_a"
	elif len(new_name) == 2:
		new_name = new_name[0] + "_" + chr(ord(new_name[1]) + 1)
	else:
		raise ValueError("invalid net name")
	return new_name