code: function unmerge(toRemove) {
      var cy = this._private.cy;
  
      if (!toRemove) {
        return this;
      }
  
      if (toRemove && string(toRemove)) {
        var selector = toRemove;
        toRemove = cy.mutableElements().filter(selector);
      }
  
      for (var i = 0; i < toRemove.length; i++) {
        this.unmergeOne(toRemove[i]);
      }
  
      return this; // chaining
    }
docs: remove eles in place on calling collection