'Get client connection.'

def _get_client(self, access_key_id=None, secret_access_key=None):

    if (self._client is None):
        client_parameters = dict(region_name=self.aws_region)
        if (access_key_id is not None):
            client_parameters.update(dict(aws_access_key_id=access_key_id, aws_secret_access_key=secret_access_key))
        if (self.endpoint_url is not None):
            client_parameters[u'endpoint_url'] = self.endpoint_url
        self._client = boto3.client(u'dynamodb', **client_parameters)
        self._get_or_create_table()
    return self._client
