A website requires that passwords only contain letters. For each character in passPhrase that is not a letter, replace the character with $\text{'}x\text{'}.$

Ex$.$ If the input is $c1PFf,$ then the output is:

New password: cxPFf

Note: isalpha$()$ returns true if a character is a letter, and false otherwise. Ex: isalpha$(\text{'}$a$\text{'})$ returns true. isalpha$(\text{'}8\text{'})$ returns false