def start_deep_check(verify=False, add_lease=False):
    """Check upon the health of me and everything I can reach.

        This is a recursive form of check(), useable only on dirnodes.

        I return a Monitor, with results that are an IDeepCheckResults
        object.

        TODO: If any of the directories I traverse are unrecoverable, the
        Monitor will report failure. If any of the files I check upon are
        unrecoverable, those problems will be reported in the
        IDeepCheckResults as usual, and the Monitor will not report a
        failure.
        """
