*
 * <h3>Capabilities</h3>
 *
 * <p>{@code Network} supports the following use cases (<a
 * href="https://github.com/google/guava/wiki/GraphsExplained#definitions">definitions of
 * terms</a>):
 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow parallel edges
 *   <li>graphs that do/don't allow self-loops

    Permissions perms = new Permissions();

    AdjustablePolicy(Permission... permissions) {
      for (Permission permission : permissions) perms.add(permission);
    }

    void addPermission(Permission perm) {
      perms.add(perm);
    }

    void clearPermissions() {
      perms = new Permissions();
    }

    @Override