input: Write a function to create a Python class that receives two strings and has methods for comparing the strings and returning whether they are equal, different, or similar up to a provided threshold.
  assert StringComparator("hello", "hello").is_equal()==True
  assert StringComparator("hello", "world").is_equal()==False
  assert StringComparator("hello", "world").is_different()==True
  assert StringComparator("hello", "halloween").is_similar(threshold=0.5)==False
  assert StringComparator("kitten", "sitting").is_similar(threshold=0.5)==True
output: class StringComparator:
      def __init__(self, str1, str2):
          self.str1 = str1
          self.str2 = str2
  
      def is_equal(self):
          return self.str1 == self.str2
  
      def is_different(self):
          return self.str1 != self.str2
  
      def is_similar(self, threshold):
          from difflib import SequenceMatcher
          similarity = SequenceMatcher(None, self.str1, self.str2).ratio()
          return similarity >= threshold