code: function(attrs, attrsToRemove) {
      _.forEach(attrs, function(val, key) {
        // shouldRemove is either an object or a boolean
        var shouldRemove = attrsToRemove[key];
        if (_.isUndefined(shouldRemove)) {
          return;
        }
  
        // Support nested object
        if (_.isPlainObject(val) && !_.isArray(val) && _.isPlainObject(shouldRemove)) {
          return this._removeAttributes(val, shouldRemove);
        }
  
        if (shouldRemove) {
          delete attrs[key];
        }
      }.bind(this));
    }
docs: Remove attributes
  
  Does not work for objects embedded inside arrays
  
  @param {Object} attrs
  @param {Object} attrsToRemove