code: function addCommand(command) {
      if (!command.name) {
          throw new Error('All registered commands must have a name');
      }
      if (command.params == null) {
          command.params = [];
      }
      if (!Array.isArray(command.params)) {
          throw new Error('command.params must be an array in ' + command.name);
      }
      // Replace the type
      command.params.forEach(function(param) {
          if (!param.name) {
              throw new Error('In ' + command.name + ': all params must have a name');
          }
          upgradeType(command.name, param);
      }, this);
      commands[command.name] = command;
  
      if (command.bindKey) {
          buildKeyHash(command);   
      }
  
      commandNames.push(command.name);
      commandNames.sort();
  }
docs: This registration method isn't like other Ace registration methods because
  it doesn't return a decorated command because there is no functional
  decoration to be done.
  TODO: Are we sure that in the future there will be no such decoration?