Python Unhashable Type Error

Currently I am creating a function called randomwalkthat takes as input the set edges, a teleport probability a and a positive integer itersand performs the random walk.

Starting from any page, the function will randomly follow links from one page to the next, teleporting to a completely random page with probability a at each iteration.

It should also store all visited states and eventually create a histogram of the frequency by which each page was visited. This histogram is what the randomwalk function will return

This is what I have so far, I'm getting an Unhashable Type error though for list. Here is the list of edges

 edges =[[0,1], [1,1], [2,0], [2,2], [2,3], [3,3], [3,4], [4,6], [5,5], [6,6], [6,3]]

def randomWalk(edges, a ,iters):
pages = list({edges[0] for edge in edges})
dict_edges = {}
for edge_from, edge_to in edges:
    if edge_from not in dict_edges:
        dict_edges[edge_from] = [edge_to]
    else:
        dict_edges[edge_from].append(edge_to)
current_page = random.choice(pages)
visit_counts_dictionary = {page:0 for page in pages}
visit_counts_dictionary[current_page] +=1
for _ in range(iters):
    if random.uniform(0,1) < a:
        current_page = random.choice(pages)
        visit_counts_dictionary[current_page] += 1
    else:
        current_page = random.choice(dict_edges[current_page])
        visit_counts_dictionary[current_page] += 1
print visit_counts_dictionary

How would I fix this?