def construct_url(base: str, endpoint: str) -> str:
  """Construct a URL from a base URL and an API endpoint.

  Args:
    base: The root address, e.g. http://api.backblaze.com/b2api/v1.
    endpoint: The path of the endpoint, e.g. /list_buckets.

  Returns:
    A URL based on the info.
  """
  return ''.join((base, endpoint))