input: Write a function to create a class named Calculator with two methods: add_two_numbers and add. The add_two_numbers method should take two arguments and return their sum. The add method should take three arguments and return their sum. If the class is correctly implemented, the provided code should produce the correct output.
  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, 7)==12
  assert Calculator().add_two_numbers(-3, 3)==0
  assert Calculator().add(1, 2, 3)==6
  assert Calculator().add(5, 5, 5)==15
  assert Calculator().add(-1, 0, 1)==0
output: 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