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.
  
  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
  
  # Test cases
  comparator = StringComparator("hello", "hello")
  assert comparator.is_equal() == True
  assert comparator.is_different() == False
  assert comparator.is_similar() == True
  
  comparator = StringComparator("hello", "world")
  assert comparator.is_equal() == False
  assert comparator.is_different() == True
  assert comparator.is_similar() == False
  
  comparator = StringComparator("kitten", "sitting")
  assert comparator.is_equal() == False
  assert comparator.is_different() == True
  assert comparator.is_similar(threshold=0.3) == True
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 = self.edit_distance(self.string1, self.string2)
     max_length = max(len(self.string1), len(self.string2))
  
     return distance / max_length < threshold
  
   def edit_distance(self, str1, str2):
     m, n = len(str1), len(str2)
     dp = [[0] * (n + 1) for _ in range(m + 1)]
  
     for i in range(m + 1):
       for j in range(n + 1):
         if i == 0:
           dp[i][j] = j
         elif j == 0:
           dp[i][j] = i
         elif str1[i-1] == str2[j-1]:
           dp[i][j] = dp[i-1][j-1]
         else:
           dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1])
  
     return dp[m][n]
  