input: Write a python function to check if a string contains an anagram of a given substring.
  assert isAnagramSubstring("listen", "silent") == True
  assert isAnagramSubstring("hello", "oell") == True
  assert isAnagramSubstring("abcdef", "ghij") == False
  assert isAnagramSubstring("anagram", "nagaram") == True
output: def isAnagramSubstring(s, sub):
      from collections import Counter
      
      sub_len = len(sub)
      sub_counter = Counter(sub)
      
      for i in range(len(s) - sub_len + 1):
          if Counter(s[i:i + sub_len]) == sub_counter:
              return True
              
      return False