def build_edges(nodes):
    """Build the forward and backward edges on the given list of ParsedNodes
    and return them as two separate dictionaries, each mapping unique IDs to
    lists of edges.
    """
    backward_edges = {}
    # pre-populate the forward edge dict for simplicity
    forward_edges = {node.unique_id: [] for node in nodes}
    for node in nodes:
        backward_edges[node.unique_id] = node.depends_on_nodes[:]
        for unique_id in node.depends_on_nodes:
            forward_edges[unique_id].append(node.unique_id)
    return _sort_values(forward_edges), _sort_values(backward_edges)
Build the forward and backward edges on the given list of ParsedNodes
    and return them as two separate dictionaries, each mapping unique IDs to
    lists of edges.