Mastering Blockchain Programming with Solidity

The increaseApproval function

This function is called by the approver to increase the approved allowed amount of the spender. This just increases the number of previously approved tokens by adding _addedValue. The function also triggers the Approval event to notify the updated approved balance:

function increaseApproval(    address _spender,    uint256 _addedValue)    public    returns (bool){    allowed[msg.sender][_spender] = (    allowed[msg.sender][_spender].add(_addedValue));    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);    return true;}

This function takes the following arguments:

• _spender: The spender's address whose approved amount is to be increased
• _addedValue: The number of tokens with which to increase the previous allowance ...