ARC0020: Not required code check

[sp-sandeshpokhrel]

At this line of ARC20: https://github.com/r001/arc20_0001/blob/main/src/main.leo#L175
Why is the self.signer==credit.owner check required. Because from my understanding I thought credit, if not owned by the self.signer, then can't be used since they will remain in encrypted form and can't be used.