No name 'config' in module 'decouple' [closed]

I'm working on a django project where i'm trying to deploy django project on heroku.for doing so i have to use decouple module, and when I'm trying to import decouple module with code as stated below

from decouple import config

getting this error No name 'config' in module 'decouple'

the complete setting.py

    import os
    from decouple import config
    from dj_database_url import parse as dburl 



**# Build paths inside the project like this: os.path.join(BASE_DIR, ...)**
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/2.2/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = config('SECRET_KEY')

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = config('DEBUG')

ALLOWED_HOSTS = ['book-cover-test.herokuapp.com']


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'corsheaders',
    'rest_framework',
    'api'
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

CORS_ORIGIN_WHITELIST = [
    "http://localhost:3000"
]

ROOT_URLCONF = 'upload.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'upload.wsgi.application'


# Database

    # https://docs.djangoproject.com/en/2.2/ref/settings/#databases

default_dburl = 'sqlite:///'+ os.path.join(BASE_DIR, 'db.sqlite3')

DATABASES = {'default': config('DATABASE_URL', default=default_dburl, cast=dburl),  
}

# Password validation
# https://docs.djangoproject.com/en/2.2/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {    'NAME':'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
      'NAME':'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
     'NAME':'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
    'NAME':'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/2.2/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/2.2/howto/static-files/

STATIC_URL = '/static/'
STATIC_ROOT = os.path.join(BASE_DIR, 'staticfiles')

MEDIA_ROOT = os.path.join(BASE_DIR, 'modia')
MEDIA_URL = '/media/'