Create a function in python compute_flow(g,dist,paths) that computes the flow across all edges, where g is the graph represented by a dictionary, dist is a dictionary with the keys being the node and the values being the distance of each node to a starting node, i, and paths is the dictionary with the keys being the nodes and the values being the number of shortest paths from i to each node. It should return a dictionary where the values are frozensets with two elements that represent an edge in the graph and the values are the flow value for the corresponding edge.