@@ -24,6 +24,8 @@ namespace Nethermind.Consensus
     {
         private readonly UInt256 _constantDifficulty;
 
+        public static readonly IDifficultyCalculator Zero = new ConstantDifficultyCalculator(UInt256.Zero);
+
         public static readonly IDifficultyCalculator One = new ConstantDifficultyCalculator(UInt256.One);
 
         public ConstantDifficultyCalculator(UInt256 constantDifficulty)
//  Copyright (c) 2021 Demerzel Solutions Limited
//  This file is part of the Nethermind library.
// 
//  The Nethermind library is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
// 
//  The Nethermind library is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
//  GNU Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with the Nethermind. If not, see <http://www.gnu.org/licenses/>.
// 

using Nethermind.Core;
using Nethermind.Int256;

namespace Nethermind.Consensus
{
    public class ConstantDifficultyCalculator : IDifficultyCalculator
    {
        private readonly UInt256 _constantDifficulty;

        public static readonly IDifficultyCalculator One = new ConstantDifficultyCalculator(UInt256.One);

        public ConstantDifficultyCalculator(UInt256 constantDifficulty)
        {
            _constantDifficulty = constantDifficulty;
        }
        
        public UInt256 Calculate(BlockHeader header, BlockHeader parent) => _constantDifficulty;
    }
}

rename to ConstantDifficulty instead of ConstantDifficultyCalculator -> or even -> Difficulty.One, Difficulty.Zero