input: Write a function to check if two strings are anagrams.
  assert is_anagram("silent", "listen") == True
  assert is_anagram("evil", "vile") == True
  assert is_anagram("fluster", "restful") == True
  assert is_anagram("prefix", "suffix") == False
  assert is_anagram("hello", "billion") == False
output: def is_anagram(str1, str2):
      return sorted(str1) == sorted(str2)