61 buffer = input.readline()  variable
62 while buffer != '':
64 	if not arrowexp.search(buffer):
69 			if regexp.search(buffer):
70 				node_set |= set([re.split('\s+',buffer,2)[1]])
72 	buffer = input.readline()  variable
88 buffer = input.readline()  variable
89 while buffer != '':
97 	if arrowexp.search(buffer):
100 		nodes = arrowexp.split(buffer)
105 					output.write(buffer)
106 	elif nodeexp.search(buffer): #this is a node line
107 		node = re.split('\s+', buffer,2)[1]
109 			output.write(buffer)
111 		output.write(buffer)
112 	buffer = input.readline()  variable