input: Write a function that takes in a list and prints a dictionary with the elements and the product of each element. If the list is empty, return an empty dictionary.
  
  assert product_of_list([7, 8, 5])=={7: 49, 8: 64, 5: 25}
  assert product_of_list([3, 4, 5])=={3: 9, 4: 16, 5: 25}
  assert product_of_list([1])=={1: 1}
  assert product_of_list([-2, -3, 5])=={-2: 4, -3: 9, 5: 25}
  assert product_of_list([])=={}
output: def product_of_list(lst):
      if not lst:
          return {}
      return {x: x * x for x in lst}