text: from typing import Set
  
  from sqlalchemy import Column
  from sqlalchemy import ForeignKey
  from sqlalchemy import Integer
  from sqlalchemy import String
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  
  Base = declarative_base()
  
  
  class B(Base):
      __tablename__ = "b"
      id = Column(Integer, primary_key=True)
      a_id: int = Column(ForeignKey("a.id"))
      data = Column(String)
  
  
  class A(Base):
      __tablename__ = "a"
  
      id = Column(Integer, primary_key=True)
      data = Column(String)
      bs = relationship(B, uselist=True)
  
  
  # EXPECTED_MYPY: List item 1 has incompatible type "A"; expected "B"
  a1 = A(bs=[B(data="b"), A()])
  
  # EXPECTED_MYPY: Incompatible types in assignment (expression has type "List[B]", variable has type "Set[B]") # noqa
  x: Set[B] = a1.bs
  