Remove useless code

Author: chenf

contracts/NestBase.sol

@@ -2,9 +2,7 @@
 
 pragma solidity ^0.8.6;
 
-import "./libs/TransferHelper.sol";
 import "./interfaces/INestGovernance.sol";
-import "./interfaces/INestLedger.sol";
 
 /// @dev Base contract of nest
 contract NestBase {

contracts/NestBatchMining.sol

@@ -6,7 +6,6 @@ import "./libs/IERC20.sol";
 import "./libs/TransferHelper.sol";
 
 import "./interfaces/INestBatchMining.sol";
-import "./interfaces/INestLedger.sol";
 
 import "./custom/ChainConfig.sol";
 import "./custom/NestFrequentlyUsed.sol";
@@ -751,17 +750,6 @@ contract NestBatchMining is ChainConfig, NestFrequentlyUsed, INestBatchMining {
         payable(to).transfer(value);
     }
 
-    /// @dev Donate to dao
-    /// @param channelId Target channelId
-    /// @param value Amount to receive
-    function donate(uint channelId, uint value) external override {
-
-        PriceChannel storage channel = _channels[channelId];
-        require(channel.opener == msg.sender, "NOM:!opener");
-        channel.rewards -= _toUInt96(value);
-        INestLedger(INestMapping(_governance).getNestLedgerAddress()).addETHReward { value: value } (channelId);
-    }
-
     /// @dev Gets the address corresponding to the given index number
     /// @param index The index number of the specified address
     /// @return The address corresponding to the given index number

contracts/NestBatchPlatform.sol

@@ -2,6 +2,7 @@
 
 pragma solidity ^0.8.6;
 
+import "./interfaces/INestMapping.sol";
 import "./NestBase.sol";
 
 /// @dev The contract is for nest builtin contract address mapping

contracts/NestLedger.sol

@@ -246,9 +246,4 @@ interface INestBatchMining {
     /// @param to Address to receive
     /// @param value Amount to receive
     function pay(uint channelId, address to, uint value) external;
-
-    /// @dev Donate to dao
-    /// @param channelId Target channelId
-    /// @param value Amount to receive
-    function donate(uint channelId, uint value) external;
 }