def construct_tagged_docker_image_name(dockerImageName, dockerImageTag=None):
    """Constructs a tagged docker image name from a Docker image name and an
  optional tag.

  Args:
    dockerImageName(str): Name of the Docker image in `namespace/image` format

    dockerImageTag(str, optional): Optional tag of the Docker image
  """
    if dockerImageTag is None:
        return dockerImageName
    else:
        return '{}:{}'.format(dockerImageName, dockerImageTag)
