first commit

contracts/helper/Migrations.sol

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+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+pragma experimental ABIEncoderV2;
+
+
+contract Migrations {
+    address public owner;
+    uint256 public last_completed_migration;
+
+    modifier restricted() {
+        if (msg.sender == owner) {
+            _;
+        }
+    }
+
+    constructor() public {
+        owner = msg.sender;
+    }
+
+    function setCompleted(uint256 completed) public restricted {
+        last_completed_migration = completed;
+    }
+
+    function upgrade(address newAddress) public restricted {
+        Migrations upgraded = Migrations(newAddress);
+        upgraded.setCompleted(last_completed_migration);
+    }
+}