input: Write a function to generate a list comprehension that returns the squared values of a given list of numbers. The function should take a list as an input and return the list comprehension.
  assert square_values([1, 2, 3, 5, 8, 13])==[1, 4, 9, 25, 64, 169]
  assert square_values([])==[]
  assert square_values([-1, -2, -3])==[1, 4, 9]
  assert square_values([0])==[0]
  assert square_values([4, -5, 6])==[16, 25, 36]
output: def square_values(numbers):
      return [x**2 for x in numbers]