input: Write a class to compare two strings and return whether they are equal, different, or similar up to a provided threshold.
  
  class StringComparator:
  
    def __init__(self, string1, string2):
      self.string1 = string1
      self.string2 = string2
  
    def is_equal(self):
      return self.string1 == self.string2
  
    def is_different(self):
      return self.string1 != self.string2
  
    def is_similar(self, threshold=0.5):
      distance = edit_distance(self.string1, self.string2)
      max_length = max(len(self.string1), len(self.string2))
  
      return distance / max_length < 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", "hella").is_similar(threshold=0.8)==True
  assert StringComparator("hello", "world").is_similar(threshold=0.2)==False
output: 
  class StringComparator:
  
    def __init__(self, string1, string2):
      self.string1 = string1
      self.string2 = string2
  
    def is_equal(self):
      return self.string1 == self.string2
  
    def is_different(self):
      return self.string1 != self.string2
  
    def is_similar(self, threshold=0.5):
      distance = edit_distance(self.string1, self.string2)
      max_length = max(len(self.string1), len(self.string2))
  
      return distance / max_length < threshold
  