input: Write a function to calculate the sum of two variables using lambda. The function should take two parameters, `a` and `b`, and return the sum of these two parameters using a lambda function.
  assert sum_with_lambda(3, 4)==7
  assert sum_with_lambda(0, 0)==0
  assert sum_with_lambda(-1, 1)==0
  assert sum_with_lambda(5, -3)==2
  assert sum_with_lambda(-5, -5)==-10
output: sum_with_lambda = lambda a, b: a + b