def METHOD_NAME(
    env_variable: str, paths: Sequence[str], separator: str = ":"
) -> str:
    """Return a string for env_variable with one of more paths prepended.
    :param env_variable: the variable to operate on.
    :param paths: one or more paths to append.
    :param separator: the separator to use.
    :returns: a shell string where one or more paths are prepended
                  before env_variable. The code takes into account the case
                  where the environment variable is empty, to avoid putting
                  a separator token at the end.
    """
    return separator.join(paths) + f"${{{env_variable}:+{separator}${env_variable}}}"