contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  // implementation of transfer token
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_value > 0);
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  // check balance user (map)
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
  }

}
function transfer(address _to, uint256 _value) public returns (bool) {
  require(_value > 0);
  require(_to != address(0));
  require(_value <= balances[msg.sender]);

  balances[msg.sender] = balances[msg.sender].sub(_value);
  balances[_to] = balances[_to].add(_value);
  emit Transfer(msg.sender, _to, _value);
  return true;
}

// implementation of transfer token