Connection with service accounts for Google APIs with "ImportError: cannot import name SignedJwtAssertionCredentials" error

api_connection.py

from oauth2client.service_account import ServiceAccountCredentials
import httplib2
import os

SCOPE = 'API_SCOPE'
ACCOUNT = 'SERVICE_ACCOUNT'
KEY = 'KEY_PATH'


def initialize():
    """
    Get credentials

    :return: credentials
    :rtype: oauth2client.service_account.ServiceAccountCredentials
    """
    cred = None
    args = {
        'service_account_email': ACCOUNT,
        'filename': KEY,
        'scopes': SCOPE,
    }

    if os.path.exists(KEY):
        cred = ServiceAccountCredentials.from_p12_keyfile(**args)

    return cred


def connect(cred):
    """
    Connect to API

    :param ServiceAccountCredentials cred: credentials
    :return: api connection
    :rtype: httplib2.Http
    """
    http = httplib2.Http()

    if cred:
        cred.refresh(http)
        http = cred.authorize(http)
    else:
        print('Credentials not found!')

    return http


def main():
    cred = initialize()
    conn = connect(cred)
    print(conn)


if __name__ == '__main__':
    main()