code: def build_edges(nodes):
      
      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)
docs: 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.