code: def from_dict(cls, coll, d):
          
          return Mark(collection=coll, operation=Operation[d[cls.FLD_OP]],
                      pos=d[cls.FLD_MARK], field=d[cls.FLD_FLD])
docs: Construct from dict
  
          :param coll: Collection for the mark
          :param d: Input
          :type d: dict
          :return: new instance
          :rtype: Mark