input: Write a Python function to check if two strings are anagrams.
  assert is_anagram('listen', 'silent') == True
  assert is_anagram('triangle', 'integral') == True
  assert is_anagram('apple', 'papel') == True
  assert is_anagram('rat', 'car') == False
  assert is_anagram('night', 'thing') == True
output: def is_anagram(str1, str2):
      return sorted(str1) == sorted(str2)