def METHOD_NAME(mapper=None):
    """
    Function that assigns object column defaults on object initialization
    time. By default calling this function applies instant defaults to all
    your models.
    Setting up instant defaults::
        from sqlalchemy_utils import force_instant_defaults
        force_instant_defaults()
    Example usage::
        class Document(Base):
            __tablename__ = 'document'
            id = sa.Column(sa.Integer, autoincrement=True)
            name = sa.Column(sa.Unicode(50))
            created_at = sa.Column(sa.DateTime, default=datetime.now)
        document = Document()
        document.created_at  # datetime object
    :param mapper: The mapper which the automatic instant defaults forcing
                   should be applied to
    """
    if mapper is None:
        mapper = sa.orm.Mapper
    sa.event.listen(mapper, 'init', instant_defaults_listener)