a pruned TP

to operate the nbprune workflow

the topic is for you to write a graph parser

given a file that looks like this

s1 10 s2
s2 20 s1
s2 30 s3
s3 20 s4

your code should

• open and read the file

• and return a dict that looks like this

{'s1': [('s2', 10)], 's2': [('s1', 20), ('s3', 30)], 's3': [('s4', 20)]}

# your code here
def graphdict(filename):
    pass