|   | 1 |  initial version  | 
If n is your number of vertices, you can for instance create a list of n empty lists as follows:
sage: L = [[] for _ in range(n)]
And then you can access the (empty) list number i (for i from 0 to n-1) using:
sage: L[i]
[]
sage: L[i].append(0)
sage: L[i]
[0]
 Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.
 
                
                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.