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class Node(Repr, Base):
    __tablename__        = 'confignode'

    name                 = Column(String, name = 'node', primary_key = True)
    last_report_time     = Column(DateTime)

GroupMember = Table(
    'configgroupmember', Base.metadata,
    Column('node', String, ForeignKey('confignode.node')),
    Column('groupid', Integer, ForeignKey('configgroup.id')),
    PrimaryKeyConstraint('node', 'groupid')
    )

class Group(Repr, Base):
    __tablename__ = "configgroup"

    id                   = Column(Integer, primary_key = True)
    name                 = Column(String)
    _parent              = Column(Integer, ForeignKey('configgroup.id'), name = 'parent')
    parent               = relationship("Group", remote_side = "Group.id")
    children             = relationship("Group", remote_side = 'Group._parent')
    nodes                = relationship(Node, secondary = GroupMember)