How to use the pynamodb.attributes.ListAttribute function in pynamodb

table_name = 'test_complex_model_async'
        host = settings.DYNAMODB_HOST

    id = NumberAttribute(hash_key=True)
    list_attr = ListAttribute(default=[])
    name = UnicodeAttribute()
    description = UnicodeAttribute()


class TestComplexModelSync(PynamoDBModel):
    class Meta:
        table_name = 'test_complex_model_sync'
        host = settings.DYNAMODB_HOST

    id = NumberAttribute(hash_key=True)
    list_attr = ListAttribute(default=[])
    name = UnicodeAttribute()
    description = UnicodeAttribute()

tab.set_document_tab_page(tab_data['page'])
        self.add_document_tab(tab)

class ProjectModel(BaseModel):
    """
    Represents a project in the database.
    """
    class Meta:
        """Meta class for Project."""
        table_name = 'cla-{}-projects'.format(stage)
        if stage == 'local':
            host = 'http://localhost:8000'      
    project_id = UnicodeAttribute(hash_key=True)
    project_external_id = UnicodeAttribute()
    project_name = UnicodeAttribute()
    project_individual_documents = ListAttribute(of=DocumentModel, default=[])
    project_corporate_documents = ListAttribute(of=DocumentModel, default=[])
    project_icla_enabled = BooleanAttribute(default=True)
    project_ccla_enabled = BooleanAttribute(default=True)
    project_ccla_requires_icla_signature = BooleanAttribute(default=False)
    project_external_id_index = ExternalProjectIndex()
    project_acl = UnicodeSetAttribute(default=set())

class Project(model_interfaces.Project): # pylint: disable=too-many-public-methods
    """
    ORM-agnostic wrapper for the DynamoDB Project model.
    """
    def __init__(self, project_id=None, project_external_id=None, project_name=None,
                 project_icla_enabled=True, project_ccla_enabled=True,
                 project_ccla_requires_icla_signature=False,
                 project_acl=None):
        super(Project).__init__()

signature_project_external_id = UnicodeAttribute(null=True)
    signature_company_signatory_id = UnicodeAttribute(null=True)
    signature_company_signatory_name = UnicodeAttribute(null=True)
    signature_company_signatory_email = UnicodeAttribute(null=True)
    signature_company_initial_manager_id = UnicodeAttribute(null=True)
    signature_company_initial_manager_name = UnicodeAttribute(null=True)
    signature_company_initial_manager_email = UnicodeAttribute(null=True)
    signature_company_secondary_manager_list = JSONAttribute(null=True)
    signature_company_signatory_index = SignatureCompanySignatoryIndex()
    signature_company_initial_manager_index = SignatureCompanyInitialManagerIndex()
    project_signature_external_id_index = SignatureProjectExternalIndex()

    # whitelists are only used by CCLAs
    domain_whitelist = ListAttribute(null=True)
    email_whitelist = ListAttribute(null=True)
    github_whitelist = ListAttribute(null=True)
    github_org_whitelist = ListAttribute(null=True)


class Signature(model_interfaces.Signature):  # pylint: disable=too-many-public-methods
    """
    ORM-agnostic wrapper for the DynamoDB Signature model.
    """

    def __init__(
            self,  # pylint: disable=too-many-arguments
            signature_id=None,
            signature_external_id=None,
            signature_project_id=None,
            signature_document_minor_version=None,
            signature_document_major_version=None,
            signature_reference_id=None,

@convert_pynamo_attribute.register(attributes.ListAttribute)
def convert_list_to_list(type, attribute, registry=None):
    if attribute.element_type:
        try:
            name = attribute.attr_name
        except KeyError:
            name = "MapAttribute"

        required = not attribute.null if hasattr(attribute, 'null') else False
        return ListOfMapToObject(description=name, required=required)
    else:
        return List(String, description=attribute.attr_name)

from bs4 import BeautifulSoup
from pynamodb.models import Model
from pynamodb.attributes import UnicodeAttribute, ListAttribute


class PortalKeyword(Model):
    """
    A DynamoDB Keyword
    """
    class Meta:
        table_name = "PortalKeyword"
        region = 'ap-northeast-2'

    portal = UnicodeAttribute(hash_key=True)
    createdAt = UnicodeAttribute(range_key=True)
    keywords = ListAttribute()


def naver_keywords_crawler():
    created_at = datetime.datetime.utcnow().isoformat()[:19]
    naver_keywords = []

    try:
        naver_resp = requests.get('https://www.naver.com/')
        naver_soup = BeautifulSoup(naver_resp.text, 'html.parser')

        for i, tag in enumerate(naver_soup.find_all('span', {'class':'ah_k'})[:20]):
            rank = i+1
            keyword = tag.get_text()

            naver_keywords.append({'rank': rank, 'keyword': keyword})

note = UnicodeAttribute(null=True)
    signature_project_external_id = UnicodeAttribute(null=True)
    signature_company_signatory_id = UnicodeAttribute(null=True)
    signature_company_signatory_name = UnicodeAttribute(null=True)
    signature_company_signatory_email = UnicodeAttribute(null=True)
    signature_company_initial_manager_id = UnicodeAttribute(null=True)
    signature_company_initial_manager_name = UnicodeAttribute(null=True)
    signature_company_initial_manager_email = UnicodeAttribute(null=True)
    signature_company_secondary_manager_list = JSONAttribute(null=True)
    signature_company_signatory_index = SignatureCompanySignatoryIndex()
    signature_company_initial_manager_index = SignatureCompanyInitialManagerIndex()
    project_signature_external_id_index = SignatureProjectExternalIndex()

    # whitelists are only used by CCLAs
    domain_whitelist = ListAttribute(null=True)
    email_whitelist = ListAttribute(null=True)
    github_whitelist = ListAttribute(null=True)
    github_org_whitelist = ListAttribute(null=True)


class Signature(model_interfaces.Signature):  # pylint: disable=too-many-public-methods
    """
    ORM-agnostic wrapper for the DynamoDB Signature model.
    """

    def __init__(
            self,  # pylint: disable=too-many-arguments
            signature_id=None,
            signature_external_id=None,
            signature_project_id=None,
            signature_document_minor_version=None,
            signature_document_major_version=None,

def has_map_or_list_attributes(cls):
        for attr_value in cls._get_attributes().values():
            if isinstance(attr_value, MapAttribute) or isinstance(attr_value, ListAttribute):
                return True
        return False

signature_reference_id = UnicodeAttribute()
    signature_reference_type = UnicodeAttribute()
    signature_type = UnicodeAttribute(default='cla')
    signature_signed = BooleanAttribute(default=False)
    signature_approved = BooleanAttribute(default=False)
    signature_sign_url = UnicodeAttribute(null=True)
    signature_return_url = UnicodeAttribute(null=True)
    signature_callback_url = UnicodeAttribute(null=True)
    signature_user_ccla_company_id = UnicodeAttribute(null=True)
    signature_project_index = ProjectSignatureIndex()
    signature_reference_index = ReferenceSignatureIndex()
    # Callback type refers to either Gerrit or GitHub
    signature_return_url_type = UnicodeAttribute(null=True)

    # whitelists are only used by CCLAs
    domain_whitelist = ListAttribute(null=True)
    email_whitelist = ListAttribute(null=True)

class Signature(model_interfaces.Signature): # pylint: disable=too-many-public-methods
    """
    ORM-agnostic wrapper for the DynamoDB Signature model.
    """
    def __init__(self, # pylint: disable=too-many-arguments
                 signature_id=None,
                 signature_external_id=None,
                 signature_project_id=None,
                 signature_document_minor_version=None,
                 signature_document_major_version=None,
                 signature_reference_id=None,
                 signature_reference_type='user',
                 signature_type=None,
                 signature_signed=False,

Represents a project in the database.
    """

    class Meta:
        """Meta class for Project."""

        table_name = "cla-{}-projects".format(stage)
        if stage == "local":
            host = "http://localhost:8000"

    project_id = UnicodeAttribute(hash_key=True)
    project_external_id = UnicodeAttribute()
    project_name = UnicodeAttribute()
    project_name_lower = UnicodeAttribute(null=True)
    project_individual_documents = ListAttribute(of=DocumentModel, default=[])
    project_corporate_documents = ListAttribute(of=DocumentModel, default=[])
    project_member_documents = ListAttribute(of=DocumentModel, default=[])
    project_icla_enabled = BooleanAttribute(default=True)
    project_ccla_enabled = BooleanAttribute(default=True)
    project_ccla_requires_icla_signature = BooleanAttribute(default=False)
    project_external_id_index = ExternalProjectIndex()
    project_acl = UnicodeSetAttribute(default=set())


class Project(model_interfaces.Project):  # pylint: disable=too-many-public-methods
    """
    ORM-agnostic wrapper for the DynamoDB Project model.
    """

    def __init__(
            self,
            project_id=None,

rval.append({attr_key: attr_class.serialize(v)})
        return rval

    def deserialize(self, values):
        """
        Decode from list of AttributeValue types.
        """
        deserialized_lst = []
        for v in values:
            class_for_deserialize = self.element_type() if self.element_type else _get_class_for_deserialize(v)
            attr_value = _get_value_for_deserialize(v)
            deserialized_lst.append(class_for_deserialize.deserialize(attr_value))
        return deserialized_lst

DESERIALIZE_CLASS_MAP = {
    LIST_SHORT: ListAttribute(),
    NUMBER_SHORT: NumberAttribute(),
    STRING_SHORT: UnicodeAttribute(),
    BOOLEAN: BooleanAttribute(),
    MAP_SHORT: MapAttribute(),
    NULL: NullAttribute()
}

SERIALIZE_CLASS_MAP = {
    dict: MapAttribute(),
    list: ListAttribute(),
    set: ListAttribute(),
    bool: BooleanAttribute(),
    float: NumberAttribute(),
    int: NumberAttribute(),
    str: UnicodeAttribute(),
}