'Initiate the client with OAuth information.
For the initial authentication with the backend `auth_key` and
`auth_secret` can be `None`. Use `get_authorize_url` and
`get_access_token` to obtain them for subsequent uses of the API.
:param c_key:       OAuth1 client key
:param c_secret:    OAuth1 client secret
:param auth_key:    OAuth1 resource owner key
:param auth_secret: OAuth1 resource owner secret'

def __init__(self, c_key, c_secret, auth_key=None, auth_secret=None):

    self.api = OAuth1Session(client_key=c_key, client_secret=c_secret, resource_owner_key=auth_key, resource_owner_secret=auth_secret, callback_uri='oob')
    self.api.headers = {'User-Agent': USER_AGENT}
