def _collect_missing_target_counter(counter_name, lookup_counter_values,
    anchor_name, missing_target_counters):
    """Collect missing target counters.

    The corresponding TargetLookupItem caches the target's page based
    counter values during pagination.

    """
    if counter_name not in lookup_counter_values:
        missing_counters = missing_target_counters.setdefault(anchor_name, [])
        if counter_name not in missing_counters:
            missing_counters.append(counter_name)
