class Father(Entity): name = Field(Unicode(100)) children = OneToMany('Child')
class Child(Entity): name = Field(Unicode(100)) father = ManyToOne('Father')
class Child1_4(Entity): name = Field(Text) parent = ManyToOne('Parent1_4')
class Language(Entity): using_options = {'auto_primarykey': False} id = Field(Unicode(50), primary_key=True) label = Field(Unicode(50))
class Child1_3(Entity): name = Field(Text) parent = ManyToOne('Parent1_3', inverse='children')
class Parent1_4(Entity): name = Field(Text) children = OneToMany('Child1_4')
class Parent1_2(Entity): name = Field(Text) children = OneToMany('Child1_2', inverse='parent')
class Child1_2(Entity): name = Field(Text)
class Engine4_4(Entity): name = Field(Text) car = ManyToOne('Car4_4')
class Car4_4(Entity): name = Field(Text) engine = OneToOne('Engine4_4')
class Engine4_3(Entity): name = Field(Text) car = ManyToOne('Car4_3', inverse='engine')
class Car4_3(Entity): name = Field(Text) engine = OneToOne('Engine4_3', inverse='car')
class Engine4_2(Entity): name = Field(Text)