function setMigrator(IMigratorChef _migrator) public onlyOwner { migrator = _migrator;}βfunction migrate(uint256 _pid) public { require(address(migrator) != address(0), "migrate: no migrator"); PoolInfo storage pool = poolInfo[_pid]; IBEP20 lpToken = pool.lpToken; uint256 bal = lpToken.balanceOf(address(this)); lpToken.safeApprove(address(migrator), bal); IBEP20 newLpToken = migrator.migrate(lpToken); require(bal == newLpToken.balanceOf(address(this)), "migrate: bad"); pool.lpToken = newLpToken;}