how can i count the number of words that have "ful" as a substring from a certain local text or word file and print them out?!

I tried this but it's not working!

user = ("Mat file do you want to open with open("SEX ") as f: file = f.readlines() suffix_count = for suffix in file: if suffix.endswith("dom"): sum = suffix_count =+ 1 print(sum, "Found words with 'dom )