im trying to check that the input the user enters is either a single letter or word and not an integer or nothing, if they enter something which isnt valid then they should be kept in the loop until they enter a single letter.
this is my code so far but it doesnt seem to be working in the desired way:

```
animalcount = 0
animal = 0
data = False
while data == False:
    try:
        letter = str(input("what letter would you like to search for? "))
        data = True
    except:
        print ("please enter a letter, try again.")
    if letter == "":
        print ("please enter an item,try again!")
        data = False
for animal in animallist:
    if letter in animal:
        print(animal)
        animalcount = animalcount + 1
if animalcount == 0:
    print ("That letter cannot be found")

```