def get_grouped_parameters(parameter_tokens):
	""" Takes a stream of tokens and separates them by the comma separator.
	
	:param parameter_tokens:	A token stream.
	:type parameter_tokens:		list
	:returns:					grouped_tokens
	:rtype:						list
	"""
	grouped_tokens = [[]]
	first_run = True
	for token in parameter_tokens:
		# The first run edge case must get rid of the empty internal list if
		# the first token is a comma
		if first_run == True and token == ",":
			grouped_tokens.pop()
		first_run = False
		
		if token == ",":
			grouped_tokens.append([])
		else:
			grouped_tokens[-1].append(token)
	return grouped_tokens