def __init__(self, api_key=None, api_url=API_URL, api_version=API_VERSION):
if api_key is None:<EOL><INDENT>api_key = os.environ.get('<STR_LIT>', None)<EOL><DEDENT>if api_key is None:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>self.api_key = api_key<EOL>self.api_url = api_url<EOL>self.api_version = api_version<EOL>
Parameters
----------
api_key: str, optional
    If not supplied uses value of envvar DIGITALOCEAN_API_KEY
api_url: str, optional
api_version: str, optional