is_isogram.py

"""
wiki: https://en.wikipedia.org/wiki/Heterogram_(literature)#Isograms
"""


defis_isogram(string: str) ->bool:
"""
 An isogram is a word in which no letter is repeated.
 Examples of isograms are uncopyrightable and ambidextrously.
 >>> is_isogram('Uncopyrightable')
 True
 >>> is_isogram('allowance')
 False
 >>> is_isogram('copy1')
 Traceback (most recent call last):
 ...
 ValueError: String must only contain alphabetic characters.
 """
ifnotall(x.isalpha() forxinstring):
raiseValueError("String must only contain alphabetic characters.")

letters=sorted(string.lower())
returnlen(letters) ==len(set(letters))


if__name__=="__main__":
input_str=input("Enter a string ").strip()

isogram=is_isogram(input_str)
print(f"{input_str} is {'an'ifisogramelse'not an'} isogram.")