code: private boolean arrayKeyValueExists(String key, String value) {
      if (visitedPost.containsKey(key)) {
        for(String s : visitedPost.get(key)) {
          if(s.equals(value)) {
            return true;
          }
        }
      }
  
      return false;
  
    }
docs: Checks whether the value exists in an ArrayList of certain key.
  
  @param key the string of the uri
  @param value the request body of the uri
  @return true or false depending whether the uri and request body have already been processed