input: 
  class Calculator:
      """
      A class that implements a calculator with methods to add two numbers and 
      another method to add three numbers.
      
      Examples:
      >>> calculator = Calculator()
      >>> calculator.add_two_numbers(1, 2)
      3
      >>> calculator.add(1, 2, 3)
      6
      """
      def __init__(self):
          pass
      
      def add_two_numbers(self, a, b):
          return a + b
  
      def add(self, a, b, c):
          return a + b + c
  
output:     
      def add_three_numbers(self, a, b, c):
          return a + b + c
  