input: Write a function to use lambda to calculate the sum of two variables. The function should take two parameters and return a lambda function that performs the sum operation. If the function is executed with the given example input, it should print 7.
  
  assert calculate_sum(3, 4) == 7
  
  def calculate_sum(a, b):
      return (lambda a, b: a + b)(a, b)
  
  calculate_sum(3, 4)
output: def calculate_sum(a, b):
      return (lambda x, y: x + y)(a, b)