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