code: function(attr, options) {
        if (!(attr in this.attributes)) return this;
        options || (options = {});
        var value = this.attributes[attr];
  
        // Run validation.
        var validObj = {};
        validObj[attr] = void 0;
        if (!options.silent && this.validate && !this._performValidation(validObj, options)) return false;
  
        // Remove the attribute.
        delete this.attributes[attr];
        delete this._escapedAttributes[attr];
        if (attr == this.idAttribute) delete this.id;
        this._changed = true;
        if (!options.silent) {
          this.trigger('change:' + attr, this, void 0, options);
          this.change(options);
        }
        return this;
      }
docs: Remove an attribute from the model, firing `"change"` unless you choose to silence it. `unset` is a noop if the attribute doesn't exist.