Document `approveAndCall` more thoroughly
@@ -50,7 +50,9 @@ contract TBTCToken is ERC20Detailed, ERC20, VendingMachineAuthority {
/// @notice Set allowance for other address and notify.
/// Allows `_spender` to spend no more than `_value` tokens
/// on your behalf and then ping the contract about it.
- /// @param _spender The address authorized to spend.
+ /// @dev The `_spender` should implement the `tokenRecipient` interface above
+ /// to receive approval notifications.
+ /// @param _spender Address of contract authorized to spend.
/// @param _value The max amount they can spend.
/// @param _extraData Extra information to send to the approved contract.
function approveAndCall(address _spender, uint256 _value, bytes memory _extraData) public returns (bool success) {
