'Gets an OpenID token, using a known Cognito ID. This known
Cognito ID is returned by GetId. You can optionally add
additional logins for the identity. Supplying multiple logins
creates an implicit link.
The OpenId token is valid for 15 minutes.
:type identity_id: string
:param identity_id: A unique identifier in the format REGION:GUID.
:type logins: map
:param logins: A set of optional name-value pairs that map provider
names to provider tokens.'

def get_open_id_token(self, identity_id, logins=None):

    params = {'IdentityId': identity_id}
    if (logins is not None):
        params['Logins'] = logins
    return self.make_request(action='GetOpenIdToken', body=json.dumps(params))
