input: Write a function to suggest a valid Python syntax to calculate the sum of two variables using lambda. The function should return the lambda expression and also provide a way to test it using given input values.
  assert suggest_lambda_sum_syntax()==('lambda a, b: a + b', 7)
  assert suggest_lambda_sum_syntax()==('lambda x, y: x + y', 7)
output: def suggest_lambda_sum_syntax():
      return ('lambda a, b: a + b', (lambda a, b: a + b)(3, 4))