input: Write a python function to filter words with exactly six letters from a list.
  assert filter_sixletter_words(["python", "java", "csharp", "kotlin", "swift", "go"])==["python", "kotlin", "swift"]
  assert filter_sixletter_words(["hello", "world", "python", "coding", "scripts"])==["python", "coding"]
  assert filter_sixletter_words(["sixlet", "seven", "eightin", "nineteen", "twenty"])==["sixlet", "eightin"]
output: def filter_sixletter_words(words):
      return [word for word in words if len(word) == 6]