input: Write a python function to concatenate two strings using a class method.
  assert ConcatStrings("Hello, ", "World!").print_concat() == None
  assert ConcatStrings("foo", "bar").print_concat() == None
  assert ConcatStrings("Test", "123").print_concat() == None
output: class ConcatStrings:
      def __init__(self, str1, str2):
          self.str1 = str1
          self.str2 = str2
  
      def print_concat(self):
          concatenated_string = self.str1 + self.str2
          print(concatenated_string)