private IEnumerable <int> PositionToTryList(int posBase1) { Helper.CheckCondition(1 <= posBase1 && posBase1 <= Count, "Position is not in range. " + posBase1.ToString()); return(SpecialFunctions.EnumerateInterleave(SpecialFunctions.EnumerateRange(posBase1, 1, -1), SpecialFunctions.EnumerateRange(posBase1 + 1, Count, +1))); }