A user can grant authorization to another address to make calls on their behalf via the Caller.callAs function. The Caller.unauthorize function allows the user to revoke the authorization of another address.
An authorized user can revoke the authorization of another authorized user of the same sender. This is because the authorized user can call the Caller.unauthorize function on behalf of the sender.
Caller.sol#L114-L118
Consider preventing calls to the Caller contract address from within the _call function.
