code: public static Map<Circuit, Collection<TileRef>> imports(Media circuitsConfig)
      {
          Check.notNull(circuitsConfig);
  
          final Xml root = new Xml(circuitsConfig);
          final Collection<Xml> nodesCircuit = root.getChildren(NODE_CIRCUIT);
          final Map<Circuit, Collection<TileRef>> circuits = new HashMap<>(nodesCircuit.size());
  
          for (final Xml nodeCircuit : nodesCircuit)
          {
              final String groupIn = nodeCircuit.readString(ATT_GROUP_IN);
              final String groupOut = nodeCircuit.readString(ATT_GROUP_OUT);
              final String circuitType = nodeCircuit.readString(ATT_CIRCUIT_TYPE);
              final CircuitType type = CircuitType.from(circuitType);
              final Circuit circuit = new Circuit(type, groupIn, groupOut);
  
              final Collection<Xml> nodesTileRef = nodeCircuit.getChildren(TileConfig.NODE_TILE);
              final Collection<TileRef> tilesRef = importTiles(nodesTileRef);
  
              circuits.put(circuit, tilesRef);
          }
  
          return circuits;
      }
docs: Import all circuits from configuration.
  
  @param circuitsConfig The circuits configuration (must not be <code>null</code>).
  @return The circuits imported.
  @throws LionEngineException If unable to read data.