input: Write a function to create a dictionary where each key is an element from the given list and the corresponding value is the product of that element with itself. 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([])=={}
output: def product_of_list(lst):
      return {x: x * x for x in lst}