input: Write a function to generate a Python script that contains a function with two parameters and returns the sum of the two parameters. The function should be named `add` and should take two parameters, `x` and `y`, and return their sum. If the script is generated correctly, it should be possible to use the `add` function to compute the sum of two numbers.
  assert add(2, 3)==5
  assert add(0, 0)==0
  assert add(-1, 1)==0
output: def add(x, y):
      return x + y