input: from typing import Callable
  
  def create_sum_lambda() -> Callable[[int, int], int]:
      """ Create a lambda function that calculates the sum of two variables.
      >>> sum_func = create_sum_lambda()
      >>> sum_func(3, 4)
      7
      """
      return lambda a, b: a + b
output:     return lambda a, b: a + b