code: public Neuron[] neurons() {
          HashMap<Integer, Neuron> hash = new HashMap<>();
          Neuron[] neurons = new Neuron[nodes.size()];
          
          int i = 0;
          for (Node node : nodes) {
              Neuron[] neighbors = new Neuron[node.edges.size()];
              neurons[i] = new Neuron(node.w, neighbors);
              hash.put(node.id, neurons[i]);
              i++;
          }
  
          i = 0;
          for (Node node : nodes) {
              int j = 0;
              for (Edge edge : node.edges) {
                  if (edge.a != node)
                      neurons[i].neighbors[j++] = hash.get(edge.a.id);
                  else
                      neurons[i].neighbors[j++] = hash.get(edge.b.id);
              }
              i++;
          }
          
          return neurons;
      }
docs: Returns the neurons in the network.
  @return the neurons in the network.