code: function(element, opt) {
  
          opt = opt || {};
          var res = [];
          // Modify the options so that it includes the `inbound` neighbors only. In other words, search backwards.
          this.search(element, function(el) {
              if (el !== element) {
                  res.push(el);
              }
          }, joint.util.assign({}, opt, { inbound: true }));
          return res;
      }
docs: Find all the predecessors of `element`. This is a reverse operation of `getSuccessors()`. If `opt.deep` is `true`, take into account embedded elements too. If `opt.breadthFirst` is `true`, use the Breadth-first search algorithm, otherwise use Depth-first search.