text: #!/usr/bin/env python
  
  import fire
  
  class Calculator(object):
      """A simple calculator class."""
  
      def add(self, number1, number2):
          """Add two numbers."""
          return number1 + number2
  
      def double(self, number):
          """Multiply input x2."""
          return 2 * number
  
  
  if __name__ == '__main__':
      fire.Fire(Calculator)
  