need help with some explanation

[vincelim99]

http://imgur.com/a/Ijcbi

n = int(input("Enter the number of vertices you want"))
FileName = input("Please input name of file:")
edgeFile = open(FileName)

#empty adj.list
adjList = n*[0]
for i in range(n):
    adjList[i]=[]

#adj.list
for line in edgeFile:
    edgePoint = line.split()
    adjList[int(edgePoint[0])].append(int(edgePoint[1]))
    adjList[int(edgePoint[1])].append(int(edgePoint[0]))

edgeFile.close
print(adjList)

This code was given by lecturer and it works and gives the result : [[1, 2], [0, 2, 3], [1, 0], [1]]
I've been trying to understand why it gives output like that,i know those are the vertices that connects but i just don't know how the table of [[1, 2], [0, 2, 3], [1, 0], [1]] is produced.
Moderator Larz60+: Added code tags. Please use in the future

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