How to use the chatterbot.constants function in ChatterBot

'chatterbot.ext.django_chatterbot',
    'tests_django',
]

CHATTERBOT = {
    'name': 'Test Django ChatterBot',
    'logic_adapters': [
        {
            'import_path': 'chatterbot.logic.BestMatch',
        },
        {
            'import_path': 'chatterbot.logic.MathematicalEvaluation',
        }
    ],
    'storage_adapter': 'chatterbot.storage.DjangoStorageAdapter',
    'django_app_name': constants.DEFAULT_DJANGO_APP_NAME,
    'initialize': False
}

MIDDLEWARE_CLASSES = (
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'django.middleware.security.SecurityMiddleware',
)

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',

tag_association_table = Table(
    'tag_association',
    Base.metadata,
    Column('tag_id', Integer, ForeignKey('tag.id')),
    Column('statement_id', Integer, ForeignKey('statement.id'))
)


class Tag(Base):
    """
    A tag that describes a statement.
    """

    name = Column(
        String(constants.TAG_NAME_MAX_LENGTH),
        unique=True
    )


class Statement(Base, StatementMixin):
    """
    A Statement represents a sentence or phrase.
    """

    confidence = 0

    text = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH)
    )

    search_text = Column(

"""

    confidence = 0

    text = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH)
    )

    search_text = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH),
        nullable=False,
        server_default=''
    )

    conversation = Column(
        String(constants.CONVERSATION_LABEL_MAX_LENGTH),
        nullable=False,
        server_default=''
    )

    created_at = Column(
        DateTime(timezone=True),
        server_default=func.now()
    )

    tags = relationship(
        'Tag',
        secondary=lambda: tag_association_table,
        backref='statements'
    )

    in_response_to = Column(

backref='statements'
    )

    in_response_to = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH),
        nullable=True
    )

    search_in_response_to = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH),
        nullable=False,
        server_default=''
    )

    persona = Column(
        String(constants.PERSONA_MAX_LENGTH),
        nullable=False,
        server_default=''
    )

    def get_tags(self):
        """
        Return a list of tags for this statement.
        """
        return [tag.name for tag in self.tags]

    def add_tags(self, *tags):
        """
        Add a list of strings to the statement as tags.
        """
        self.tags.extend([
            Tag(name=tag) for tag in tags

name = Column(
        String(constants.TAG_NAME_MAX_LENGTH),
        unique=True
    )


class Statement(Base, StatementMixin):
    """
    A Statement represents a sentence or phrase.
    """

    confidence = 0

    text = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH)
    )

    search_text = Column(
        String(constants.STATEMENT_TEXT_MAX_LENGTH),
        nullable=False,
        server_default=''
    )

    conversation = Column(
        String(constants.CONVERSATION_LABEL_MAX_LENGTH),
        nullable=False,
        server_default=''
    )

    created_at = Column(
        DateTime(timezone=True),

from chatterbot.conversation import StatementMixin
from chatterbot import constants
from django.db import models
from django.utils import timezone
from django.conf import settings


DJANGO_APP_NAME = constants.DEFAULT_DJANGO_APP_NAME
STATEMENT_MODEL = 'Statement'
TAG_MODEL = 'Tag'

if hasattr(settings, 'CHATTERBOT'):
    """
    Allow related models to be overridden in the project settings.
    Default to the original settings if one is not defined.
    """
    DJANGO_APP_NAME = settings.CHATTERBOT.get(
        'django_app_name',
        DJANGO_APP_NAME
    )
    STATEMENT_MODEL = settings.CHATTERBOT.get(
        'statement_model',
        STATEMENT_MODEL
    )

def __init__(self, **kwargs):
        super().__init__(**kwargs)

        self.django_app_name = kwargs.get(
            'django_app_name',
            constants.DEFAULT_DJANGO_APP_NAME
        )

search_text = models.CharField(
        max_length=constants.STATEMENT_TEXT_MAX_LENGTH,
        blank=True
    )

    conversation = models.CharField(
        max_length=constants.CONVERSATION_LABEL_MAX_LENGTH
    )

    created_at = models.DateTimeField(
        default=timezone.now,
        help_text='The date and time that the statement was created at.'
    )

    in_response_to = models.CharField(
        max_length=constants.STATEMENT_TEXT_MAX_LENGTH,
        null=True
    )

    search_in_response_to = models.CharField(
        max_length=constants.STATEMENT_TEXT_MAX_LENGTH,
        blank=True
    )

    persona = models.CharField(
        max_length=constants.PERSONA_MAX_LENGTH
    )

    tags = models.ManyToManyField(
        TAG_MODEL,
        related_name='statements'
    )

"""
Default ChatterBot settings for Django.
"""
from django.conf import settings
from chatterbot import constants


CHATTERBOT_SETTINGS = getattr(settings, 'CHATTERBOT', {})

CHATTERBOT_DEFAULTS = {
    'name': 'ChatterBot',
    'storage_adapter': 'chatterbot.storage.DjangoStorageAdapter',
    'django_app_name': constants.DEFAULT_DJANGO_APP_NAME
}

CHATTERBOT = CHATTERBOT_DEFAULTS.copy()
CHATTERBOT.update(CHATTERBOT_SETTINGS)

"""
These factories are used to generate fake data for testing.
"""
import factory
from chatterbot.ext.django_chatterbot import models
from chatterbot import constants
from factory.django import DjangoModelFactory


class StatementFactory(DjangoModelFactory):

    text = factory.Faker(
        'text',
        max_nb_chars=constants.STATEMENT_TEXT_MAX_LENGTH
    )

    class Meta:
        model = models.Statement


class ResponseFactory(DjangoModelFactory):

    statement = factory.SubFactory(StatementFactory)

    response = factory.SubFactory(StatementFactory)

    class Meta:
        model = models.Response