docs: def _model_unique(ins):
      """ Get unique constraints info
  
      :type ins: sqlalchemy.orm.mapper.Mapper
      :rtype: list[tuple[str]]
      """
      unique = []
      for t in ins.tables:
          for c in t.constraints:
              if isinstance(c, UniqueConstraint):
                  unique.append(tuple(col.key for col in c.columns))
      return unique