def concept_is_bad(uri):
    """
    Skip concepts that are unlikely to be useful.

    A concept containing too many underscores is probably a long, overly
    specific phrase, possibly mis-parsed. A concept with a colon is probably
    detritus from a wiki.
    """
    return ':' in uri or uri.count('_') >= 3 or uri.startswith('/a/'
        ) or uri.count('/') <= 2
