input: Write a function to create a Python list comprehension that returns the squared values of a given list. The function takes a list as input and returns a new list with each element squared.
  assert list_squares([1, 2, 3, 5, 8, 13])==[1, 4, 9, 25, 64, 169]
  assert list_squares([-1, -2, 3, -5, 8])==[1, 4, 9, 25, 64]
  assert list_squares([])==[]
output: return [x**2 for x in input_list]