code: def changes(self):
          
          output = []
          if self.status() is self.UNMODIFIED:
              output = [self.formatter % (' ', self.key, self.old_value)]
          elif self.status() is self.ADDED:
              output.append(self.formatter % ('+', self.key, self.new_value))
          elif self.status() is self.REMOVED:
              output.append(self.formatter % ('-', self.key, self.old_value))
          elif self.status() is self.MODIFIED:
              output.append(self.formatter % ('-', self.key, self.old_value))
              output.append(self.formatter % ('+', self.key, self.new_value))
          return output
docs: Returns a list of changes to represent the diff between
          old and new value.
  
          Returns:
              list: [string] representation of the change (if any)
                  between old and new value