from pydantic import BaseModel
from typing import Optional


class AllOptional(type(BaseModel)):
    def __new__(cls, name, bases, namespaces, **kwargs):
        annotations = namespaces.get('__annotations__', {})
        for base in bases:
            annotations.update(getattr(base, '__annotations__', {}))
        for field in annotations:
            if not field.startswith('__'):
                annotations[field] = Optional[annotations[field]]
        namespaces['__annotations__'] = annotations

        # Set default values
        for field in annotations:
            if not field.startswith('__') and field not in namespaces:
                namespaces[field] = None  # set default value to None only if it's not already set

        return super().__new__(cls, name, bases, namespaces, **kwargs)