':param region: Endpoint region.
:type region: ``str``
:param url: Endpoint URL.
:type url: ``str``
:param endpoint_type: Endpoint type (external / internal / admin).
:type endpoint_type: ``str``'

def __init__(self, region, url, endpoint_type='external'):

    if (endpoint_type not in self.VALID_ENDPOINT_TYPES):
        raise ValueError(('Invalid    type:    %s' % endpoint_type))
    self.region = region
    self.url = url
    self.endpoint_type = endpoint_type
