input: Write a function to calculate the sum of two variables using a lambda function and print the result. The function should accept two variables as input and return the lambda function.
  assert calculate_sum(3, 4) == 7
  assert calculate_sum(5, 7) == 12
  assert calculate_sum(0, 0) == 0
  assert calculate_sum(-1, 1) == 0
  assert calculate_sum(-3, -4) == -7
output: def calculate_sum(a, b):
      return lambda: a + b