code: function(raw){
                  var clone = canReflect.serialize(raw);
                  var value = clone.filter[prop];
                  delete clone.filter[prop];
                  if(value) {
                      canReflect.assign(clone.filter, value);
                  }
  
                  return clone;
              }
docs: {filter: {$where: {a:b}}} -> {filter: {a:b}}