input: Write a python function to check if two strings are anagrams.
  assert is_anagram("listen", "silent") == True
  assert is_anagram("hello", "billion") == False
  assert is_anagram("evil", "vile") == True
  assert is_anagram("fluster", "restful") == True
  assert is_anagram("python", "typhon") == True
  assert is_anagram("apple", "pabble") == False
output: def is_anagram(s1, s2):
      return sorted(s1) == sorted(s2)