def dns(addrs):
    """Formats the usage of DNS servers.

    Very important to define this parameter when ever running a container as
    Ubuntu resolves over the loopback network, and RHEL doesn't.

    If you don't supply this in a docker run command, than users running RHEL
    based Linux cannot run automation built from Ubuntu based containers.
    Same thing for Ubuntu OS users running RHEL based containers.

    :Returns: String

    :param addrs: A comma separated list of DNS IPs
    :type addrs: String
    """
    if addrs:
        return [x.strip(' \n') for x in addrs.split(',')]
    return None