public IEnumerator <KeyValuePair <T, double> > GetEnumerator()
{
throw new NotImplementedException("Maybe a bug, should be divided by _totalEventCountWithNoise");
long count = _store.TotalCopiesCount;
return(_store.Select(kvp => new KeyValuePair <T, double>(kvp.Key, kvp.Value / (double)count)).GetEnumerator());
}