contract StandardToken is ERC20, BasicToken {

  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);

    emit Transfer(_from, _to, _value);
    return true;
  }

}
/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://github.com/ethereum/EIPs/issues/20
 */
function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
  require(_to != address(0));

  balances[_from] = balances[_from].sub(_value);
  balances[_to] = balances[_to].add(_value);

  emit Transfer(_from, _to, _value);
  return true;
}

/**
 * @dev Transfer tokens from one address to another
 * @param _from address The address which you want to send tokens from
 * @param _to address The address which you want to transfer to
 * @param _value uint256 the amount of tokens to be transferred
 */