code: function loadForBook(book) {
      var logger = book.getLogger();
  
      // List the dependencies
      var requirements = listDepsForBook(book);
  
      // List all plugins installed in the book
      return findForBook(book)
      .then(function(installedMap) {
          var missing = [];
          var plugins = requirements.reduce(function(result, dep) {
              var name = dep.getName();
              var installed = installedMap.get(name);
  
              if (installed) {
                  var deps = installedMap
                      .filter(function(plugin) {
                          return plugin.getParent() === name;
                      })
                      .toArray();
  
                  result = result.concat(deps);
                  result.push(installed);
              } else {
                  missing.push(name);
              }
  
              return result;
          }, []);
  
          // Convert plugins list to a map
          plugins = Immutable.List(plugins)
              .map(function(plugin) {
                  return [
                      plugin.getName(),
                      plugin
                  ];
              });
          plugins = Immutable.OrderedMap(plugins);
  
          // Log state
          logger.info.ln(installedMap.size + ' plugins are installed');
          if (requirements.size != installedMap.size) {
              logger.info.ln(requirements.size + ' explicitly listed');
          }
  
          // Verify that all plugins are present
          if (missing.length > 0) {
              throw new Error('Couldn\'t locate plugins "' + missing.join(', ') + '", Run \'gitbook install\' to install plugins from registry.');
          }
  
          return Promise.map(plugins, function(plugin) {
              return loadPlugin(book, plugin);
          });
      });
  }
docs: Load all plugins in a book
  
  @param {Book}
  @return {Promise<Map<String:Plugin>}