input: 
  def calculate_sum_using_lambda(a: int, b: int) -> lambda:
      """ Calculate the sum of two integers using a lambda function.
      >>> calculate_sum_using_lambda(3, 4)(3, 4)
      7
      >>> calculate_sum_using_lambda(10, 20)(10, 20)
      30
      """
  
output:     return lambda x, y: x + y