How to use the federation.entities.mixins.CreatedAtMixin function in federation

from federation.entities.mixins import (
    PublicMixin, TargetIDMixin, ParticipationMixin, CreatedAtMixin, RawContentMixin, OptionalRawContentMixin,
    EntityTypeMixin, ProviderDisplayNameMixin, RootTargetIDMixin, BaseEntity)
from federation.utils.network import fetch_content_type


class Accept(CreatedAtMixin, TargetIDMixin, BaseEntity):
    """An acceptance message for some target."""

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        # ID not required for accept
        self._required.remove('id')


class Image(OptionalRawContentMixin, CreatedAtMixin, BaseEntity):
    """Reflects a single image, possibly linked to another object."""
    url: str = ""
    name: str = ""
    height: int = 0
    width: int = 0
    inline: bool = False
    media_type: str = ""

    _default_activity = ActivityType.CREATE
    _valid_media_types: Tuple[str] = (
        "image/jpeg",
        "image/png",
        "image/gif",
    )

    def __init__(self, *args, **kwargs):

_relationship_valid_values = ["sharing", "following", "ignoring", "blocking"]

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._required += ["relationship"]

    def validate_relationship(self):
        """Ensure relationship is of a certain type."""
        if self.relationship not in self._relationship_valid_values:
            raise ValueError("relationship should be one of: {valid}".format(
                valid=", ".join(self._relationship_valid_values)
            ))


class Profile(CreatedAtMixin, OptionalRawContentMixin, PublicMixin, BaseEntity):
    """Represents a profile for a user."""
    atom_url = ""
    email = ""
    gender = ""
    image_urls = None
    location = ""
    name = ""
    nsfw = False
    public_key = ""
    tag_list = None
    url = ""
    username = ""
    inboxes: Dict = None

    _allowed_children = (Image,)

super().__init__(*args, **kwargs)
        self._required += ["following"]
        # ID not required for follow
        self._required.remove('id')


class Post(RawContentMixin, PublicMixin, CreatedAtMixin, ProviderDisplayNameMixin, BaseEntity):
    """Reflects a post, status message, etc, which will be composed from the message or to the message."""
    location = ""
    url = ""

    _allowed_children = (Image,)
    _default_activity = ActivityType.CREATE


class Reaction(ParticipationMixin, CreatedAtMixin, BaseEntity):
    """Represents a reaction to another object, for example a like."""
    participation = "reaction"
    reaction = ""

    _default_activity = ActivityType.CREATE
    _reaction_valid_values = ["like"]

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._required += ["reaction"]

    def validate_reaction(self):
        """Ensure reaction is of a certain type.

        Mainly for future expansion.
        """