input: Write a function to create a class named Calculator with two methods, add_two_numbers which takes two arguments and returns their sum, and add which takes three arguments and returns their sum. The class should not take any initial arguments.
  
  class Calculator:
   def __init__(self):
     pass
      
   def add_two_numbers(self, a, b):
     return a + b
  
   def add(self, a, b, c):
     return a + b + c
  
  assert Calculator().add_two_numbers(1, 2) == 3
  assert Calculator().add_two_numbers(5, 10) == 15
  assert Calculator().add_two_numbers(-1, 1) == 0
  assert Calculator().add(1, 2, 3) == 6
  assert Calculator().add(5, 10, 15) == 30
  assert Calculator().add(-1, 1, 0) == 0
output: def __init__(self):
      pass
      
  def add_two_numbers(self, a, b):
      return a + b
  
  def add(self, a, b, c):
      return a + b + c