About the sets in python

import stringalphabet = set(string.ascii_lowercase)def is_pangram_alternative(s):    return not (set(alphabet) - set(s))input_string = 'The quick brown fox jumps over the lazy dog'if is_pangram_alternative(input_string):    print("Yes")else:    print("No")

in the above code when this happens set(alphabet) - set(s) it eliminates all the lowercase alphabets and there will be only uppercase and whitespaces remaining as per the difference between the sets it should return false but how does it produces the results correctly