input: Below is an instruction that describes a task. Write a response that appropriately completes the request.
  
  ### Instruction:
  Suggest a valid Python syntax to calculate the sum of two variables using lambda
  
  ### Input:
  a = 3, b = 4
  
  ### Output:
  sum = lambda a, b : a + b
  print(sum(3,4))
   函数头的描述写法见以下格式：
  
  from typing import List
  
  def sum_with_lambda(a: int, b: int) -> int:
      """Calculate the sum of two variables using lambda function.
      >>> sum_with_lambda(3, 4)
      7
      >>> sum_with_lambda(-1, 5)
      4
      """
output:     return (lambda a, b: a + b)(a, b)