code: def __init__(
      self,
      is_metadata: bool,
      impl: DefaultImpl,
      const: UniqueConstraint,
  ) -> None:
      self.impl = impl
      self.const = const
      self.name = sqla_compat.constraint_name_or_none(const.name)
      self._sig = tuple(sorted([col.name for col in const.columns]))
      self._is_metadata = is_metadata
  
imports: from __future__ import annotations
  from typing import Any
  from typing import ClassVar
  from typing import Dict
  from typing import Generic
  from typing import NamedTuple
  from typing import Optional
  from typing import Sequence
  from typing import Tuple
  from typing import Type
  from typing import TYPE_CHECKING
  from typing import TypeVar
  from typing import Union
  from sqlalchemy.sql.schema import Constraint
  from sqlalchemy.sql.schema import ForeignKeyConstraint
  from sqlalchemy.sql.schema import Index
  from sqlalchemy.sql.schema import UniqueConstraint
  from typing_extensions import TypeGuard
  from ..None import util
  from ..util import sqla_compat
label_desc: Use image node_id 2 to create a new _uq_constraint_sig object from inherited base classes: _constraint_sig with example: obj = _uq_constraint_sig(is_metadata, impl, const)