from typing import Generic, TypeVar

from pydantic import ValidationError
from pydantic.generics import GenericModel

T = TypeVar('T')


class InnerT(GenericModel, Generic[T]):
    inner: T


class OuterT(GenericModel, Generic[T]):
    outer: T
    nested: InnerT[T]


nested = InnerT[int](inner=1)
print(OuterT[int](outer=1, nested=nested))
try:
    nested = InnerT[str](inner='a')
    print(OuterT[int](outer='a', nested=nested))
except ValidationError as e:
    print(e)