input: Write a Python class to modify the case of the string input and provide methods to convert the string to uppercase, lowercase, and title case. Define the class with an initializer that accepts a string.
  
  class StringCaseModifier:
      def __init__(self, string):
          self.string = string
  
      def to_upper(self):
          return self.string.upper()
  
      def to_lower(self):
          return self.string.lower()
      
      def to_title(self):
          return self.string.title()
  
  if __name__ == '__main__':
      assert StringCaseModifier('Hello World').to_upper() == 'HELLO WORLD'
      assert StringCaseModifier('Hello World').to_lower() == 'hello world'
      assert StringCaseModifier('Hello World').to_title() == 'Hello World'
      assert StringCaseModifier('hello world').to_upper() == 'HELLO WORLD'
      assert StringCaseModifier('HELLO WORLD').to_lower() == 'hello world'
      assert StringCaseModifier('hELLO wORLD').to_title() == 'Hello World'
output: class StringCaseModifier:
      def __init__(self, string):
          self.string = string
  
      def to_upper(self):
          return self.string.upper()
  
      def to_lower(self):
          return self.string.lower()
      
      def to_title(self):
          return self.string.title()