Discuss the below:
Q: Edward lost his hands while serving in Iraq, so he is unable to sign his name. He recently borrowed $500 from his sister Patty, and at her request, he agreed to sign a promissory note, payable to her, in the amount of $500. He did this by stamping the note with a stamp that he had made following his injury; the stamp simply states his name. Patty is now worried that the promissory note is worthless because Edward did not actually sign it. Is she correct? Explain.