input: Write a function to create a list comprehension that returns the squared values of a given list. The function should take a list of integers as input and return a list of their squared values. If the input list is empty, the function should return an empty list.
  assert squared_values([1, 2, 3, 5, 8, 13])==[1, 4, 9, 25, 64, 169]
  assert squared_values([])==[]
output: def squared_values(lst):
      return [x**2 for x in lst]