Add EIP: Non-Fungible Key Bound Token

assets/eip-6809/.gitignore

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+node_modules/
+build/
+.env
+.vscode
+package-lock.json

assets/eip-6809/README.md

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+# EIP 6809 implementation
+
+This project is a reference implementation of EIP-6809.
+
+Try running some of the following tasks:
+
+```shell
+npm i
+truffle compile
+truffle test
+```

assets/eip-6809/contracts/IKBT721.sol

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+// SPDX-License-Identifier: CC0-1.0
+pragma solidity ^0.8.17;
+
+interface IKBT721 {
+    event AccountSecured(address indexed _account, uint256 _noOfTokens);
+    event AccountResetBinding(address indexed _account);
+    event SafeFallbackActivated(address indexed _account);
+    event AccountEnabledTransfer(
+        address _account,
+        uint256 _tokenId,
+        uint256 _time,
+        address _to,
+        bool _anyToken
+    );
+    event AccountEnabledApproval(
+        address _account,
+        uint256 _time,
+        uint256 _numberOfTransfers
+    );
+    event Ingress(address _account, uint256 _tokenId);
+    event Egress(address _account, uint256 _tokenId);
+
+    struct AccountHolderBindings {
+        address firstWallet;
+        address secondWallet;
+    }
+
+    struct FirstAccountBindings {
+        address accountHolderWallet;
+        address secondWallet;
+    }
+
+    struct SecondAccountBindings {
+        address accountHolderWallet;
+        address firstWallet;
+    }
+
+    struct TransferConditions {
+        uint256 tokenId;
+        uint256 time;
+        address to;
+        bool anyToken;
+    }
+
+    struct ApprovalConditions {
+        uint256 time;
+        uint256 numberOfTransfers;
+    }
+
+    function addBindings(
+        address _keyWallet1,
+        address _keyWallet2
+    ) external returns (bool);
+
+    function getBindings(
+        address _account
+    ) external view returns (AccountHolderBindings memory);
+
+    function resetBindings() external returns (bool);
+
+    function safeFallback() external returns (bool);
+
+    function allowTransfer(
+        uint256 _tokenId,
+        uint256 _time,
+        address _to,
+        bool _allTokens
+    ) external returns (bool);
+
+    function getTransferableFunds(
+        address _account
+    ) external view returns (TransferConditions memory);
+
+    function allowApproval(
+        uint256 _time,
+        uint256 _numberOfTransfers
+    ) external returns (bool);
+
+    function getApprovalConditions(
+        address account
+    ) external view returns (ApprovalConditions memory);
+
+    function getNumberOfTransfersAllowed(
+        address _account,
+        address _spender
+    ) external view returns (uint256);
+
+    function isSecureWallet(address _account) external returns (bool);
+
+    function isSecureToken(uint256 _tokenId) external returns (bool);
+}