code: function isAllowedReferral(referral) {
    log.trace('isAllowedReferral(%j)', referral);
    if (! defaultReferrals.enabled) return(false);
    if (! referral) return(false);
  
    return(! _.any(defaultReferrals.exclude, function(exclusion) {
      var re = new RegExp(exclusion, "i");
      return(re.test(referral));
    }));
  }
docs: Checks to see if the specified referral or "chase" is allowed.
  @param {String} referral The referral to inspect.
  @returns {Boolean} True if the referral should be followed, false if otherwise.