contract Under { mapping(address => uint) balances; uint public totalSupply; constructor(uint _initialSupply) public { balances[msg.sender] = totalSupply = _initialSupply; } function sendeth(address _to, uint _value) public returns (bool) { require(balances[msg.sender] - _value >= 0); balances[msg.sender] -= _value; balances[_to] += _value; return true; } function balanceOf(address _owner) public view returns (uint balance) { return balances[_owner]; } }