input: Write a function to create a class named Calculator in Python that implements two methods to add two and three numbers respectively. If the given numbers to add are integers, return the sum of those integers. If the inputs are strings, concatenate them and return the result. If any of the inputs are neither integers nor strings, return "Invalid input".
  
  class Calculator:
      def __init__(self):
          pass
      
      def add_two_numbers(self, a, b):
          if isinstance(a, (int, str)) and isinstance(b, (int, str)):
              return a + b
          else:
              return "Invalid input"
  
      def add_three_numbers(self, a, b, c):
          if isinstance(a, (int, str)) and isinstance(b, (int, str)) and isinstance(c, (int, str)):
              return a + b + c
          else:
              return "Invalid input"
  
  calculator = Calculator()
  assert calculator.add_two_numbers(1, 2) == 3
  assert calculator.add_two_numbers("Hello ", "World") == "Hello World"
  assert calculator.add_two_numbers(1, "Hello") == "Invalid input"
  assert calculator.add_three_numbers(1, 2, 3) == 6
  assert calculator.add_three_numbers("Hello ", "World", "!") == "Hello World!"
  assert calculator.add_three_numbers(1, "Hello", 3) == "Invalid input"
  assert calculator.add_three_numbers(1, 2, "3") == "Invalid input"
output: 
  def __init__(self):
      pass
  
  def add_two_numbers(self, a, b):
      if isinstance(a, (int, str)) and isinstance(b, (int, str)):
          return a + b
      else:
          return "Invalid input"
  
  def add_three_numbers(self, a, b, c):
      if isinstance(a, (int, str)) and isinstance(b, (int, str)) and isinstance(c, (int, str)):
          return a + b + c
      else:
          return "Invalid input"
  