def make_unique_ngrams ( s , n ) : return set ( s [ i : i + n ] for i in range ( len ( s ) - n + 1 ) )
create a set of all letters in a string python
Make a set of unique n - grams from a string .
def make_unique_ngrams(s, n):
    """Make a set of unique n-grams from a string."""
    return set(s[i:i + n] for i in range(len(s) - n + 1))