python - How do I provide error checking to ensure user input only allows letters and provides a looping error message if numbers are typed? -

i trying provide looping error message user customername input user receives error message if type other letters aa - zz,(i don't want allow user input numbers specifically). operate similar 1 used customerage input( provided example). cant seem figure out correct code accomplish this. can provide insight?

customername = input('enter name: ')  customerage = int(input('enter age: ')) while customerage <= 15 or customerage >= 106:     print('invalid entry')     customerage = int(input('enter age: ')) 

after reviewing answers received (thanks goes out of help). coded , appears operating correctly.

customer_name = input('please enter name: ') while not customer_name.isalpha():     print('invalid entry')     customer_name = input('please enter name: ')